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igomit [66]
3 years ago
5

Simplify the expression by using a double angle formula cos^2 4theta-sin^2 4theta

Mathematics
1 answer:
Nikitich [7]3 years ago
6 0
Double angle formula for cos(2x) is
cos(2x)=cos^2(x)-sin^2(x)

Substitute x=4theta, then
cos(8theta)=cos^2(4theta)-sin^2(4theta)
=>
cos^2(4theta)-sin^2(4theta) = cos(8theta)
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Find the volume of the solid formed by revolving the region bounded by LaTeX: y = \sqrt{x} y = x and the lines LaTeX: y = 1 y =
Strike441 [17]

Answer:

The volume is:

\displaystyle\frac{37\pi}{10}

Step-by-step explanation:

See the sketch of the region in the attached graph.

We set the integral using washer method:

\displaystyle\int_a^b\pi r^2dx

Notice here the radius of the washer is the difference of the given curves:

x-\sqrt{x}

So the integral becomes:

\displaystyle\int_1^4\pi(x-\sqrt{x})^2dx

We solve it:

Factor \pi out and distribute the exponent (you can use FOIL):

\displaystyle\pi\int_1^4x^2-2x\sqrt{x}+x\,dx

Notice: x\sqrt{x}=x\cdot x^{1/2}=x^{3/2}

So the integral becomes:

\displaystyle\pi\int_1^4x^2-2x^{3/2}+x\,dx

Then using the basic rule to evaluate the integral:

\displaystyle\pi\left[\frac{x^3}{3}-\frac{2x^{5/2}}{5/2}+\frac{x^2}{2}\right|_1^4

Simplifying a bit:

\displaystyle\pi\left[\frac{x^3}{3}-\frac{4x^{5/2}}{5}+\frac{x^2}{2}\right|_1^4

Then plugging the limits of the integral:

\displaystyle\pi\left[\frac{4^3}{3}-\frac{4(4)^{5/2}}{5}+\frac{4^2}{2}-\left(\frac{1}{3}-\frac{4}{5}+\frac{1}{2}\right)\right]

Taking the root (rational exponents):

\displaystyle\pi\left[\frac{4^3}{3}-\frac{4(2)^{5}}{5}+\frac{4^2}{2}-\left(\frac{1}{3}-\frac{4}{5}+\frac{1}{2}\right)\right]

Then doing those arithmetic computations we get:

\displaystyle\frac{37\pi}{10}

6 0
3 years ago
Pls help me i need it​
Delvig [45]

Answer:

13=x

Step-by-step explanation:

Side-spliting theorem

21/(x-4)=14/6

cross multiply

21*6=14*(x-4)

distribute 14

126=14x-56

add 56 to both sides

126+56=14x-56+56

leaving you with

182=14x

Divide both sides by 14 to get x by itself

182/14=14x/14

13=x

4 0
3 years ago
Please Help! Solve the equation for x.
SOVA2 [1]

Answer:

A

Step-by-step explanation:

Given

\frac{1}{3} x - 8 = - 12 ( multiply through by 3 to clear the fraction )

x - 24 = - 36 ( add 24 to both sides )

x = - 12 → A

6 0
3 years ago
Simplify each expression, #1: 4(f+2g) - 4g +f. #2: 5g(9m-2) + 3g
Serjik [45]

Answer:

1) 5f

2) 45gm-7g

Step-by-step explanation:

hope this helped!

7 0
3 years ago
In a random sample of 205 people, 149 said that they watched educational television. Find the 95% confidence interval of the tru
tensa zangetsu [6.8K]

Answer: Given a sample of 200, we are 90% confident that the true proportion of people who watched educational TV is between 72.1% and 81.9%.

Step-by-step explanation:

\frac{154}{200} =0.77

1-0.77=0.23

\sqrt{\frac{(0.77)(0.23)}{200} }=0.049

0.77±0.049< 0.819, 0.721

6 0
3 years ago
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