How would I simplify these expressions? (Pre-Calculus) I know that you are supposed to multiply all of these to do so, but every time I do that, I still get the wrong answer. My textbook says that these are the answers:
19: -15 + 8i
21: 8 + 6i
23: 34
25: 85
Could anyone explain how they got these answers? Mine are way off. Is the book just wrong? In #21, how would 3 times 3 equal 8 in the answer? Am I missing something?

How Would I Simplify These Expressions? (Pre-Calculus) I Know That You Are Supposed To Multiply All Of

Answers

Answer 1

Since you have the answers, I'll just show the steps on how to get there.

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Problem 19

[tex](1+4i)^2\\\\(1+4i)(1+4i)\\\\1*1 + 1*4i + 4i*1 + 4i*4i\\\\1 + 4i + 4i + 16i^2\\\\1 + 4i + 4i + 16(-1)\\\\1 + 4i + 4i-16\\\\(1-16) + (4i+4i)\\\\(1-16) + (4+4)i\\\\-15 + 8i\\\\[/tex]

Keep in mind that [tex]i = \sqrt{-1}[/tex] by definition. Squaring both sides leads to [tex]i^2 = -1[/tex]

In the second step, I used the idea that x^2 = x*x. Right after that, I used the FOIL rule to expand everything out.

============================================================

Problem 21

We could follow the same idea as problem 19, but I'll use a different approach.

[tex](A+B)^2 = A^2+2AB+B^2\\\\(3+i)^2 = 3^2 + 2*3*i + i^2\\\\(3+i)^2 = 9 + 6i - 1\\\\(3+i)^2 = 8 + 6i\\\\[/tex]

The formula on the first line is the perfect square binomial formula.

============================================================

Problem 23

The FOIL rule can be used if you want, but I'll use the difference of squares rule instead.

[tex](m+n)(m-n) = m^2 - n^2\\\\(3+5i)(3-5i) = (3)^2 - (5i)^2\\\\(3+5i)(3-5i) = 9 - 25i^2\\\\(3+5i)(3-5i) = 9 - 25(-1)\\\\(3+5i)(3-5i) = 9 + 25\\\\(3+5i)(3-5i) = 34\\\\[/tex]

It turns out that multiplying any complex number of the form a+bi with its conjugate a-bi will result in a purely real number (that has no imaginary part). More specifically: [tex](a+bi)(a-bi) = a^2+b^2[/tex]

============================================================

Problem 25

We could use the difference of squares rule again, but I'll show a different approach. This time using the distribution rule. The FOIL rule could also be used if you wanted.

[tex](6+7i)(6-7i)\\\\x(6-7i)\\\\6x-7xi\\\\6(x)-7i(x)\\\\6(6+7i)-7i(6+7i)\\\\6(6)+6(7i)-7i(6)-7i(7i)\\\\36+42i-42i-49i^2\\\\36-49(-1)\\\\36+49\\\\85\\\\[/tex]

I used x = 6+7i and the substitution property to help distribute. Lines 3 and 6 are where distribution is applied.


Related Questions

A shirt that normally cost $30 is on sale for $21.75 what percent of the regular price is the sale price

Answers

Answer: 72.5%

Step-by-step explanation:

I used trial and error to figure this out.

I first found a quarter of 30 which is 7.5, so the percentage is near 75% since when 7.5 is times by 3 it becomes 22.5 which is close. Then I found what one is by dividing 30 by 100 and guessed the percentages getting closer to the answer basing on whether my last answer was to low or high and found 72.5% of 30 is 21.75 so the answer is 72.5%.

(1.2•10^9) divided by (3•10^5)

Answers

Answer:

4000

Step-by-step explanation: First multiply the first two equations and will give you 1200000000 divided by 300000. Now logically 12/3is 4  so u do the same in the equation and it gives you 4000. Pls give brainly if i was right

Answer:

4000

Step-by-step explanation:

(1.2•10^9) divided by (3•10^5)

(1.2 * 10^9) : (3 * 10^5) =

(1.2 * 1000000000) : (3 * 100000) =

1200000000 : 300000 =

4000

Suppose an annuity pays 7.0% annual interest, compounded annually. If you invest $3,000 every year for 5 years, what percentage of the balance in the account is interest earned?
Round your answer to the nearest hundredth of a percent.

Answers

Answer:

  13.05%

Step-by-step explanation:

The value of an ordinary annuity earning interest compounded annually is ...

  A = P((1 +r)^n -1)/r . . . . . interest rate r for n years on principal payments P

For this account, the balance after 5 years will be ...

  A = 3000((1 +.07)^5 -1)/0.07 = 3000·5.750739

The sum of payments is ...

  payment total = 3000·5

Then the amount of interest is ...

  3000·(5.750739 -5) = 3000·0.750739

and the fraction that is of the account balance is ...

  (3000·0.750739)/(3000·5.750739) × 100% ≈ 13.05%

About 13.05% of the balance is interest earned.

Original price of shorts $53.95 Discount 30% Tax 4.5?
Please help what’s the correct answer ???

Answers

Answer:

72.8325

Step-by-step explanation:

I think it is that

Simplify the expression. w+w+5w

Answers

Answer:

w+w+5w = 7w

Step-by-step explanation:

Answer:

7w

Step-by-step explanation:

plzz help asap plzzzzz

Answers

Answer:

5.45 then 6.454 then 5425 then 12825

Step-by-step explanation:

THE SIDES OF A TRIANGLE ARE IN THE RATIO 4:4:3. A.WHAT KIND OF TRIANGLE IS IT? B. CALCULATE THE SMALLEST ANGLE OF THE TRIANGLE TO THE NEAREST DEGREE.

Answers

Answer:

1

Step-by-step explanation:

Team A beat Team B by 15 points in a football game . If a total of 35 points were scored , what was the final score of the game ?

I WILL MARK YOU A BRAINLIEST​

Answers

Answer:

25-10  (25 - A and 10 - B)

Step-by-step explanation:

25 - 10 equals the 15 point margin

25 plus 10 equals the 35 point score combined

Hope it helps

100 POINTS!
A local theater has a maximum capacity of 1000 people. For their latest production, adult tickets cost $25 and youth tickets cost $12.5. The theater needs to make at least 15,000 for the show to continue.
Write and graph a system of linear equations, and write two possible solutions.

Answers

Answer:

a+y≤1000 and 25a+12.50y>15000

Step-by-step explanation:

If x−3=5, what is the value of 2(x+4)?

Answers

Answer:

24

Step-by-step explanation:

x-3=5, solve for x so that x=5+3

now put this in place of x in the expression 2(x+4)

2[(5+3)+4]

2(8+4)

2(12)

24

We have x - 3 = 5 => x = 8
So 2(x+4) = 2(8+4) = 2. 12 = 24

Ok done. Thank to me:>

I need help on this ASAP… Line A passes through the points (-4,5) and (0,2). Line B…

Answers

Answer:

Parallel lines: Line B and C

Perpendicular lines: Line A and B; Line A and C

Step-by-step explanation:

To answer this question, we only need to find the slope of each equation. The formula for slope is attached in a picture.

LINE A

Substituting the first line into the formula, we will get...

(2 - 5)/(0 -(-4))

-3/4

LINE B

Substituting the second line's points into the formula we will get...

(2 - 6)/(3 - 6)

-4/-3

4/3

LINE C

Substituting the third line's points into the formula we will get...

(3 -(-1)/(0 -(-3))

4/3

So, parallel lines have the same slope, right? Since line b and line c have the same slope, they are parallel.

And, perpendicular lines have negative reciprocal slopes, right? (reciprocal means x/y -> y/x) Since -3/4 and 4/3 are negative reciprocals of each other, they are perpendicular.

Therefore...

Parallel lines: Line B and C

Perpendicular lines: Line A and B; Line A and C

Estimate the quotient for 608 divided by 23

Answers

Answer:

18

Step-by-step explanation:

Answer:

30

Step-by-step explanation:

When estimating we round to the nearest 1.s.f

Thus...

608 rounded to the nearest 1sf

= 600

and....

23 rounded to the nearest 1sf

=20

Therefore- 600÷ 20 = 30

Hope this helped you- have a good day bro cya)

7.
Identify the vertex of the parabola.



A. (1, 2)

B. (−2, −1)

C. (−1, −2)

D. (−3, 2)

Answers

Answer: I can't find the answer :(

B. (−2, −1)

Step-by-step explanation: I don't know :(

From when I am looking at the graph it looks like the answer would be

P= (-2, -1)

Q= (1, -2)

Line l is a reflection in the x-axis of line k. Write an equation that represents line k.

Answers

Answer:

(-4,3)

Step-by-step explanation:

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Answer: y = (5/3)x + -1

Step-by-step explanation:

The slope is -5/3, so since its a reflection in the x - axis, the new slope would be the opposite, 5/3. Now for the +1, you just have to find the y intercept by plotting the dots at the opposite version of the y number that is already there. For example because the point (0,1) has 1 as its y number, you make it into -1, and for example if you have the point (3,-4) since -4 is the y number you change it to 4.

Please I did help with this

Answers

Answer:

13.1

Step-by-step explanation:

.........................

Answers

Answer:

[tex]2[/tex]

Step-by-step explanation:

Let [tex][n][/tex] denote the area of some polygon [tex]n[/tex].

The sum of the area of quadrilaterals BCDE and MNDE is equal to [tex][ABC]-([MBE]+[NDC]+AMN])[/tex] (big triangle subtracting the three smaller triangles that aren't part of BCDE or MNDE).

Let the area of triangle ABC be [tex]\alpha[/tex].

Triangle AMN is similar to triangle ABC. Because their side lengths are in ratio 1:2 respectively, the ratio of the area of triangle AMN to triangle ABC is [tex]1:2^2=1:4[/tex].

Therefore, [tex]\displaystyle [AMN]=\frac{1}{4}[ABC]=\frac{1}{4}\alpha[/tex].

Now for triangle NDC, NDC is similar to triangle AMC. Since M is the midpoint of AB, AMC is half the area of ABC. The ratio of the side lengths between triangle NDC and triangle AMC is [tex]1:2[/tex] because the D is the midpoint of MC, so it follows the ratio of their areas must be [tex]1:4[/tex], respectively.

Therefore, [tex]\displaystyle[NDC]=\frac{1}{4}[AMC]=\frac{1}{8}[ABC]=\frac{1}{8}\alpha[/tex].

We can use the same concept for triangle MEB. Triangle MEB is similar to triangle ANB, and the ratio of their sides is also [tex]1:2[/tex], since E is the midpoint of BN. Their areas are in the ratio [tex]1:2^2=1:4[/tex] and we have [tex]\displaystyle [MBE]=\frac{1}{4}[ANB]=\frac{1}{8}\alpha[/tex].

Thus,

[tex]\displaystyle \frac{[ABC]}{[BCDE]+[MNDE]}=\frac{\alpha}{\alpha-\frac{1}{4}\alpha-\frac{1}{8}\alpha-\frac{1}{8}\alpha}=\frac{\alpha}{0.5\alpha}=\frac{1}{\frac{1}{2}}=\boxed{2}[/tex]

In a triangle, the exterior angle is twice of each of the interior opposite angles. The exterior angle is 120°.Find the measure of each interior opposite angle of the triangle.
Pls no Spam. 35 points is the prize

Answers

Answer:

Let X be other interior opposite angle of a △XYZ.

Let Y be the third angle.

Exterior angle is equal to sum of interior opposite angles.

120

o

=30

o

+∠X

⇒∠X=90

o

Now, Sum of interior angles of a triangle is 180

o

⇒90

o

+30

o

+∠Y=180

o

⇒∠Y=180

o

−120

o

=60

o

Step-by-step explanation:

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sets if 98% of households have at least one television set and 4 households are selected, find the probability that at least one household has a television set.

Answers

Using the binomial distribution, it is found that there is a 0.99999984 = 99.999984% probability that at least one household has a television set.

For each household, there are only two possible outcomes, either it has at least one television set, or it does not. The probability of a household having at least one television set is independent of any other household, which means that the binomial distribution is used to solve this question.

Binomial probability distribution

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]

The parameters are:

x is the number of successes. n is the number of trials. p is the probability of a success on a single trial.

In this problem:

4 households are selected, hence [tex]n = 4[/tex].98% have at least one television set, hence [tex]p = 0.98[/tex]

The probability that at least one household has a television set is:

[tex]P(X \geq 1) = 1 - P(X = 0)[/tex]

In which:

[tex]P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}[/tex]

[tex]P(X = 0) = C_{4,0}.(0.98)^{0}.(0.02)^{4} = 0.00000016[/tex]

Then:

[tex]P(X \geq 1) = 1 - P(X = 0) = 1 - 0.00000016 = 0.99999984 [/tex]

0.99999984 = 99.999984% probability that at least one household has a television set.

A similar problem is given at https://brainly.com/question/24863377

In the equation y ≈7x-9,if x≥2, then what is the value of y?​

Answers

Answer:

y[tex]\geq[/tex]5

Step-by-step explanation:

7(2)-9

14-9

5

y[tex]\geq[/tex]5

Violet is playing a board game with her friends. She earned 78 points during the game, and she receives a game-end bonus for achieving her secret objective. With her bonus, Violet came in second place with 91 points. Let b be the number of points Violet earned for the game-end bonus. Write and solve the equation for b.

Answers

Answer:

78 + B = 91...

91 - 78 = B

91 - 78 = 13

B = 13

Step-by-step explanation:

what is the area of the triangle?

Answers

Answer:
The second one (B) I think hope this is correct! Have a good day! :) or night

Given f(x) = 2x - 5 , find the average rate of change of f(x) from x = 2 to x = 5?

Answers

[tex]slope = m = \cfrac{rise}{run} \implies \cfrac{ f(x_2) - f(x_1)}{ x_2 - x_1}\impliedby \begin{array}{llll} average~rate\\ of~change \end{array}\\\\[-0.35em] \rule{34em}{0.25pt}\\\\ f(x)=2x - 5 \quad \begin{cases} x_1=2\\ x_2=5 \end{cases}\implies \cfrac{f(5)-f(2)}{5-2}\implies \cfrac{[2(5)-5]~~ - ~~[2(2)-5]}{3} \\\\\\ \cfrac{5-(-1)}{3}\implies \cfrac{5+1}{3}\implies 2[/tex]

Haala buys 13 identical shirts and 22 identical ties for £363.01 the cost of the shirt is £15.35 find the cost of the tie

Answers

Using linear system of equations, the cost tie is £7.43.

Linear equations -

In everyday life, we can utilize linear equations to compare prices, make predictions, create budgets, and more. When all of the variables have a highest power of one, an equation is considered to be linear. Each variable is reliant on the others. A one-degree equation is another name for this kind of equation. Continue reading to learn how to solve a linear equation in one or two variables using its standard form, formula, graph, and rules.

Given,

Haala buys 13 identical shirts and 22 identical ties for £363.01 the cost of the shirt is £15.35,

According to question,

let cost of shirt = x

cost of tie = y

Now putting it in the equation,

13x + 22y = 363.01

given x = 15.35

⇒ y = 363.01 - 13(15.35) / 22

y = 363.01 - 199.55 / 22

y = 7.43

To learn more about linear system of equations from given link

https://brainly.com/question/25858757

#SPJ1

Which equation is linear? y=x4 y=xy –x3 ОООС f(x) = 3х + 1 y=xУ​

Answers

Answer:

f(x) = 3х + 1

Step-by-step explanation:

Please check the mcq in the following picture and thank you

Answers

Answer 2nd one

Step-by-step explanation:

A calculator is selling for $80 with an 8.5% tax. How much will you pay in tax for the calculator?

Answers

Answer:

$86.80

Step-by-step explanation:

If ΔPQR ≅ ΔTSR, what are the congruent corresponding parts?

Answers

Answer:

If ΔPQR ≅ ΔTSR

Angles:

P and T

Q and S

R and R

Lines:

PQ and TS

QR and SR

PR and TR

Can someone help with question #4 please

Answers

Answer:

4,0 is the right ok I am a professor

Write an equation for the nth term of the arithmetic sequence –1, –3, –5, –7,

Answers

Answer:

[tex]a_n=-1+(n-1)(-2)[/tex]

Step-by-step explanation:

The arithmetic sequence formula looks like this:

[tex]a_n=a_1+(n-1)d[/tex]

where aₙ is the nth term, a₁ is the first term, n is the index, and d is the common difference.

Each consecutive term is decreased by 2 over the last, so d = 2. The first term is -1 of course, so you can write this equation:

[tex]a_n=-1+(n-1)(-2)[/tex]

Just to confirm:

[tex]a_n=-1+(n-1)(-2)\\a_3=-1+(2)(-2)\\a_3=-1-4\\a_3=-5[/tex]

And it works, -5 is the 3rd term in the sequence.

Answer:

[tex]a_{n}[/tex] = 1 - 2n

Step-by-step explanation:

The nth term of an arithmetic sequence is

[tex]a_{n}[/tex] = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Here a₁ = - 1 and d = a₂ - a₁ = - 3 - (- 1) = - 3 + 1 = - 2 , then

[tex]a_{n}[/tex] = - 1 - 2(n - 1) = - 1 - 2n + 2 = - 2n + 1 = 1 - 2n

Solve the triangles for X: include the steps if you can

Answers

Answer:

10) x=9

11) x=25

Step-by-step explanation:

a triangle is 180º total

10)   2x+8x+90=180

10x=90

x=9

11) 3x+1+2x+2+2x+2=180

7x+5=180

7x=175

x=25

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