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3 years ago

Help please I forgot

Mathematics

1 answer:

Gre4nikov [31]3 years ago

8 0

Answer:

.3636363636363636363636363636363636363...so on so forth.

Step-by-step explanation:

repeating

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Use the distributive property to solve the equation 28 - (3x + 4) = 2(x + 6) + 5

Shalnov [3]

1.) 28-3x-4= 2x+12+x
2.) 24-3x= 3x+12
3.)24-6x=12
4.)-6x=-12
5.)x=2

7 0

2 years ago

Evaluate the integral, show all steps please!

Aloiza [94]

Answer:

$\displaystyle \int \dfrac{1}{(9-x^2)^{\frac{3}{2}}}\:\:\text{d}x=\dfrac{x}{9\sqrt{9-x^2}} +\text{C}$

Step-by-step explanation:

Fundamental Theorem of Calculus

$\displaystyle \int \text{f}(x)\:\text{d}x=\text{F}(x)+\text{C} \iff \text{f}(x)=\dfrac{\text{d}}{\text{d}x}(\text{F}(x))$

If differentiating takes you from one function to another, then integrating the second function will take you back to the first with a constant of integration.

Given indefinite integral:

$\displaystyle \int \dfrac{1}{(9-x^2)^{\frac{3}{2}}}\:\:\text{d}x$

Rewrite 9 as 3² and rewrite the 3/2 exponent as square root to the power of 3:

$\implies \displaystyle \int \dfrac{1}{\left(\sqrt{3^2-x^2}\right)^3}\:\:\text{d}x$

Integration by substitution

$\boxed{\textsf{For }\sqrt{a^2-x^2} \textsf{ use the substitution }x=a \sin \theta}$

$\textsf{Let }x=3 \sin \theta$

$\begin{aligned}\implies \sqrt{3^2-x^2} & =\sqrt{3^2-(3 \sin \theta)^2}\\ & = \sqrt{9-9 \sin^2 \theta}\\ & = \sqrt{9(1-\sin^2 \theta)}\\ & = \sqrt{9 \cos^2 \theta}\\ & = 3 \cos \theta\end{aligned}$

Find the derivative of x and rewrite it so that dx is on its own:

$\implies \dfrac{\text{d}x}{\text{d}\theta}=3 \cos \theta$

$\implies \text{d}x=3 \cos \theta\:\:\text{d}\theta$

Substitute everything into the original integral:

$\begin{aligned}\displaystyle \int \dfrac{1}{(9-x^2)^{\frac{3}{2}}}\:\:\text{d}x & = \int \dfrac{1}{\left(\sqrt{3^2-x^2}\right)^3}\:\:\text{d}x\\\\& = \int \dfrac{1}{\left(3 \cos \theta\right)^3}\:\:3 \cos \theta\:\:\text{d}\theta \\\\ & = \int \dfrac{1}{\left(3 \cos \theta\right)^2}\:\:\text{d}\theta \\\\ & = \int \dfrac{1}{9 \cos^2 \theta} \:\: \text{d}\theta\end{aligned}$

Take out the constant:

$\implies \displaystyle \dfrac{1}{9} \int \dfrac{1}{\cos^2 \theta}\:\:\text{d}\theta$

$\textsf{Use the trigonometric identity}: \quad\sec^2 \theta=\dfrac{1}{\cos^2 \theta}$

$\implies \displaystyle \dfrac{1}{9} \int \sec^2 \theta\:\:\text{d}\theta$

$\boxed{\begin{minipage}{5 cm}\underline{Integrating $\sec^2 kx$}\\\\$\displaystyle \int \sec^2 kx\:\text{d}x=\dfrac{1}{k} \tan kx\:\:(+\text{C})$\end{minipage}}$

$\implies \displaystyle \dfrac{1}{9} \int \sec^2 \theta\:\:\text{d}\theta = \dfrac{1}{9} \tan \theta+\text{C}$

$\textsf{Use the trigonometric identity}: \quad \tan \theta=\dfrac{\sin \theta}{\cos \theta}$

$\implies \dfrac{\sin \theta}{9 \cos \theta} +\text{C}$

$\textsf{Substitute back in } \sin \theta=\dfrac{x}{3}:$

$\implies \dfrac{x}{9(3 \cos \theta)} +\text{C}$

$\textsf{Substitute back in }3 \cos \theta=\sqrt{9-x^2}:$

$\implies \dfrac{x}{9\sqrt{9-x^2}} +\text{C}$

Learn more about integration by substitution here:

brainly.com/question/28156101

brainly.com/question/28155016

4 0

2 years ago

Answer these pls Hshshsjjdhdnnddndndbdbdnx

ivann1987 [24]

1. 4/7 2. 1/2 3. 28/105 4. 20 or 20/1

5. 12 or 12/1 6. 9 or 9/1 7. 33/30 or 1 3/30

8. 16/60 or 4/15 9. 15/20 or 3/4

10. 10/24 or 5/12 11. 4 19/24

12. 68/45 or 1 23/45 13. 3/4 of time

14. 1/8 (not 100% sure)

4 0

3 years ago

A bag of chips contains 145 calories per serving. Each bag of chips contain 3 servings. How many calories are in 2 bags of chips

dybincka [34]

Answer:

870

Step-by-step explanation:

you take the calories per serving, 145, and multiply it by the number of servings in the bag, 3. this gives you 435, the number of calories in a bag. then you take the number of calories in a bag times the number of bags. you get 870

7 0

3 years ago

Which expression is equivalent to v147?

Svet_ta [14]

7v3 is the radical simplified... to do this you can use multiple methods. I like to use a factor tree.

Here’s a link to a website that explains some different methods of solving:

http://m.moomoomath.com/?url=http://www%2emoomoomath%2ecom%2fsimplyfing%2dradicals%2ehtml#2653

6 0

3 years ago