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algol [13]
3 years ago
10

Your friend multiplied complex numbers and expressions as shown. Find the error in your friends work. Then factor the expression

correctly. Show work please.
(4-7i)(4+7i)=16+28i-28i+49i^2
=16-49
=-33
Mathematics
1 answer:
MaRussiya [10]3 years ago
6 0

Answer:

  = 16+49 = 65

Step-by-step explanation:

The error is at the end of the first line. (-7i)(7i) = -49i² ≠ +49i².

The correct work is ...

  (4-7i)(4+7i)=16+28i-28i-49i^2

  = 16+49

  = 65

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4 0
3 years ago
Pi/24 is the solution for 4cos2 (4x) - 3 = 0<br><br> True or false
inessss [21]

Answer:

True.

Step-by-step explanation:

Given,

4cos2 (4x) - 3 = 0

Now, 4π/24 = π/6

Or, cos π/6 = √3/2

Or, cos^2 π/6 = 3/4

Or, 4 cos^2 π/6 = 3

Now, Left Hand Side= 4cos2 (4x) - 3

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Here, Left Hand Side= Right Hanad Side. So, 4cos2 (4x) - 3=0 is true.

5 0
3 years ago
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What is the volume of a square pyramids
frozen [14]

Answer:

\large\boxed{V=75\ in^3}

Step-by-step explanation:

The formula ogf a volume of  a pyramid:

V=\dfrac{1}{3}BH

B - area of a base

H - height

We have a base length a = 5 in and a height H = 9 in.

In the base we have a square. The formula of an area of a square is:

B=a^2

Substitute:

B=5^2=25\ in^2

Calculate the volume:

V=\dfrac{1}{3}(25)(9)=(25)(3)=75\ in^3

7 0
3 years ago
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swat32

Answer:

350 miles

Step-by-step explanation:

Let x represent the miles driven

The cost with the first plan will be represented by 0.40x + 70

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Set these 2 expressions equal to each other and solve for x:

0.40x + 70 = 0.60x

70 = 0.20x

350 = x

So, Susan will have to drive 350 miles for the cost to be the same

4 0
3 years ago
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natulia [17]

Answer:

x = 9/11

Step-by-step explanation:

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Divide both sides by 11

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x = 9/11

8 0
3 years ago
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