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3 years ago

Find the sum of 9-4i and it’s complex conjugate

1 answer:

4 0

The complex conjugate of something is essentially just taking the opposite sign of the imaginary part. The following are complex conjugates:

a + bi

a - bi

In this case the complex conjugate of 9 - 4i is 9 + 4i

Now we must add them together like so:

(9 - 4i) + (9 + 4i)

9 - 4i + 9 + 4i

^^^Combine like terms

(9 + 9) + (-4i + 4i)

18 + 0

As you can see when you add complex conjugates your answer will be a real number

Hope this helped!

~Just a girl in love with Shawn Mendes

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Cost of a comic book: 3.95<br> Markup: 20%

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3 years ago

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3 years ago

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Electric charge is distributed over the disk x2 + y2 ≤ 16 so that the charge density at (x, y) is rho(x, y) = 2x + 2y + 2x2 + 2y

professor190 [17]

Answer:

Required total charge is $256\pi$ coulombs per square meter.

Step-by-step explanation:

Given electric charge is dristributed over the disk,

$x^2=y^2\leq 16$ so that the charge density at (x,y) is,

$\rho (x,y)=2x+2y+2x^2+2y^2$

To find total charge on the disk let Q be the total charge and $x=r\cos\theta,y=r\sin\theta$ so that,

$Q={\int\int}_Q\rho(x,y) dA$ where A is the surface of disk.

$=\int_{0}^{2\pi}\int_{0}^{4}(2x+2y+2x^2+2y^2)dA$

$=\int_{0}^{2\pi}\int_{0}^{4}(2r\cos\theta+2r\sin\theta+2r^2 \cos^{2}\theta+2r^2\sin^2\theta)rdrd\theta$

$=2\int_{0}^{2\pi}\int_{0}^{4}r^2(\cos\theta+\sin\theta)drd\theta+2\int_{0}^{2\pi}\int_{0}^{4}r^3drd\theta$

$=\frac{2}{3}\int_{0}^{2\pi}(\sin\theta+\cos\theta)\Big[r^3\Big]_{0}^{4}d\theta+2\int_{0}^{2\pi}\Big[\frac{r^4}{4}\Big]d\theta$

$=\frac{128}{3}\int_{0}^{2\pi}(\sin\theta+\cos\theta)d\theta+128\int_{0}^{2\pi}d\theta$

$=\frac{128}{3}\Big[\sin\theta-\cos\theta\Big]_{0}^{2\pi}+128\times 2\pi$

$=\frac{128}{3}\Big[\sin 2\pi-\cos 2\pi-\sin 0+\cos 0\Big]+256\pi$

$=256\pi$

Hence total charge is $256\pi$ coulombs per square meter.

3 0

3 years ago

In one area, the lowest angle of elevation of the sun in winter is 27.5°. Find the minimum distance x that a plant needing full

Alex73 [517]

Answer:

The minimum distance x that a plant needing full sun can be placed from a fence that is 5 feet high is 4.435 ft

Step-by-step explanation:

Here we have the lowest angle of elevation of the sun given as 27.5° and the height of the fence is 5 feet.

We will then find the position to place the plant where the suns rays can get to the base of the plant

Note that the fence is in between the sun and the plant, therefore we have

Height of fence = 5 ft.

Angle of location x from the fence = lowest angle of elevation of the sun, θ

This forms a right angled triangle with the fence as the height and the location of the plant as the base

Therefore, the length of the base is given as

Height × cos θ

= 5 ft × cos 27.5° = 4.435 ft

The plant should be placed at a location x = 4.435 ft from the fence.

8 0

3 years ago

Need help on these, thank you!

Minchanka [31]

Where are you come from

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3 years ago