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2 years ago

Select 3 answer plz

Mathematics

1 answer:

choli [55]2 years ago

7 0

Answer:

y=3cos(x)

y=\sin(2x)+3y=sin(2x)+3

y=\tan(x)+3y=tan(x)+3

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Pweasee help!!!!!!!!!!!!!

Oduvanchick [21]

Answer:

B. $\dfrac{1}{3}x-\dfrac{1}{4}y-\dfrac{4}{5}+\dfrac{1}{3}x-\dfrac{1}{4}y$

Step-by-step explanation:

Consider all options:

A. In the expression

$\dfrac{1}{3}x-\dfrac{1}{4}y-\dfrac{4}{5}+\dfrac{1}{3}x+\dfrac{1}{4}y$

combine the like terms:

$\left(\dfrac{1}{3}x+\dfrac{1}{3}x\right)+\left(-\dfrac{1}{4}y+\dfrac{1}{4}y\right)-\dfrac{4}{5}$

Use distributive property:

$x\left(\dfrac{1}{3}+\dfrac{1}{3}\right)+y\left(-\dfrac{1}{4}+\dfrac{1}{4}\right)-\dfrac{4}{5}=\dfrac{2}{3}x-\dfrac{4}{5}$

This option is false.

2. In the expression

$\dfrac{1}{3}x-\dfrac{1}{4}y-\dfrac{4}{5}+\dfrac{1}{3}x-\dfrac{1}{4}y$

combine the like terms:

$\left(\dfrac{1}{3}x+\dfrac{1}{3}x\right)+\left(-\dfrac{1}{4}y-\dfrac{1}{4}y\right)-\dfrac{4}{5}$

Use distributive property:

$x\left(\dfrac{1}{3}+\dfrac{1}{3}\right)+y\left(-\dfrac{1}{4}-\dfrac{1}{4}\right)-\dfrac{4}{5}=\dfrac{2}{3}x-\dfrac{1}{2}y-\dfrac{4}{5}$

This option is true.

3. In the expression

$\dfrac{1}{3}x-\dfrac{1}{4}y-\dfrac{1}{5}-\dfrac{1}{3}x-\dfrac{3}{5}-\dfrac{1}{4}y$

combine the like terms:

$\left(\dfrac{1}{3}x-\dfrac{1}{3}x\right)+\left(-\dfrac{1}{4}y-\dfrac{1}{4}y\right)+\left(-\dfrac{1}{5}-\dfrac{3}{5}\right)$

Use distributive property:

$x\left(\dfrac{1}{3}-\dfrac{1}{3}\right)+y\left(-\dfrac{1}{4}-\dfrac{1}{4}\right)-\dfrac{4}{5}=-\dfrac{1}{2}y-\dfrac{4}{5}$

This option is false.

4. In the expression

$\dfrac{1}{3}x-\dfrac{1}{4}y+\dfrac{2}{5}+\dfrac{1}{3}x-\dfrac{2}{5}-\dfrac{1}{4}y$

combine the like terms:

$\left(\dfrac{1}{3}x+\dfrac{1}{3}x\right)+\left(-\dfrac{1}{4}y-\dfrac{1}{4}y\right)+\left(\dfrac{2}{5}-\dfrac{2}{5}\right)$

Use distributive property:

$x\left(\dfrac{1}{3}+\dfrac{1}{3}\right)+y\left(-\dfrac{1}{4}-\dfrac{1}{4}\right)=\dfrac{2}{3}x-\dfrac{1}{2}y$

This option is false.

7 0

2 years ago

Solve 5(y - 10) = -5

leonid [27]

Answer:

y = 9

Step-by-step explanation:

Trying to get the variable alone is the main goal in solving these

to get the variable alone here we can divide both sides by 5, which gets us

y - 10 = -1

now we can add 10 to both sides to get y = 9

8 0

1 year ago

Calculus, question 5 to 5a

Llana [10]

5. Let $x = \sin(\theta)$ . Note that we want this variable change to be reversible, so we tacitly assume 0 ≤ θ ≤ π/2. Then

$\cos(\theta) = \sqrt{1 - \sin^2(\theta)} = \sqrt{1 - x^2}$

and $dx = \cos(\theta) \, d\theta$ . So the integral transforms to

$\displaystyle \int \frac{x^3}{\sqrt{1-x^2}} \, dx = \int \frac{\sin^3(\theta)}{\cos(\theta)} \cos(\theta) \, d\theta = \int \sin^3(\theta) \, d\theta$

Reduce the power by writing

$\sin^3(\theta) = \sin(\theta) \sin^2(\theta) = \sin(\theta) (1 - \cos^2(\theta))$

Now let $y = \cos(\theta)$ , so that $dy = -\sin(\theta) \, d\theta$ . Then

$\displaystyle \int \sin(\theta) (1-\cos^2(\theta)) \, d\theta = - \int (1-y^2) \, dy = -y + \frac13 y^3 + C$

Replace the variable to get the antiderivative back in terms of x and we have

$\displaystyle \int \frac{x^3}{\sqrt{1-x^2}} \, dx = -\cos(\theta) + \frac13 \cos^3(\theta) + C$

$\displaystyle \int \frac{x^3}{\sqrt{1-x^2}} \, dx = -\sqrt{1-x^2} + \frac13 \left(\sqrt{1-x^2}\right)^3 + C$

$\displaystyle \int \frac{x^3}{\sqrt{1-x^2}} \, dx = -\frac13 \sqrt{1-x^2} \left(3 - \left(\sqrt{1-x^2}\right)^2\right) + C$

$\displaystyle \int \frac{x^3}{\sqrt{1-x^2}} \, dx = \boxed{-\frac13 \sqrt{1-x^2} (2+x^2) + C}$

6. Let $x = 3\tan(\theta)$ and $dx=3\sec^2(\theta)\,d\theta$ . It follows that

$\cos(\theta) = \dfrac1{\sec(\theta)} = \dfrac1{\sqrt{1+\tan^2(\theta)}} = \dfrac3{\sqrt{9+x^2}}$

since, like in the previous integral, under this reversible variable change we assume -π/2 < θ < π/2. Over this interval, sec(θ) is positive.

Now,

$\displaystyle \int \frac{x^3}{\sqrt{9+x^2}} \, dx = \int \frac{27\tan^3(\theta)}{\sqrt{9+9\tan^2(\theta)}} 3\sec^2(\theta) \, d\theta = 27 \int \frac{\tan^3(\theta) \sec^2(\theta)}{\sqrt{1+\tan^2(\theta)}} \, d\theta$

The denominator reduces to

$\sqrt{1+\tan^2(\theta)} = \sqrt{\sec^2(\theta)} = |\sec(\theta)| = \sec(\theta)$

and so

$\displaystyle 27 \int \tan^3(\theta) \sec(\theta) \, d\theta = 27 \int \frac{\sin^3(\theta)}{\cos^4(\theta)} \, d\theta$

Rewrite sin³(θ) just like before,

$\displaystyle 27 \int \frac{\sin(\theta) (1-\cos^2(\theta))}{\cos^4(\theta)} \, d\theta$

and substitute $y=\cos(\theta)$ again to get

$\displaystyle -27 \int \frac{1-y^2}{y^4} \, dy = 27 \int \left(\frac1{y^2} - \frac1{y^4}\right) \, dy = 27 \left(\frac1{3y^3} - \frac1y\right) + C$

Put everything back in terms of x :

$\displaystyle \int \frac{x^3}{\sqrt{9+x^2}} \, dx = 9 \left(\frac1{\cos^3(\theta)} - \frac3{\cos(\theta)}\right) + C$

$\displaystyle \int \frac{x^3}{\sqrt{9+x^2}} \, dx = 9 \left(\frac{\left(\sqrt{9+x^2}\right)^3}{27} - \sqrt{9+x^2}\right) + C$

$\displaystyle \int \frac{x^3}{\sqrt{9+x^2}} \, dx = \boxed{\frac13 \sqrt{9+x^2} (x^2 - 18) + C}$

2(b). For some constants a, b, c, and d, we have

$\dfrac1{x^2+x^4} = \dfrac1{x^2(1+x^2)} = \boxed{\dfrac ax + \dfrac b{x^2} + \dfrac{cx+d}{x^2+1}}$

3(a). For some constants a, b, and c,

$\dfrac{x^2+4}{x^3-3x^2+2x} = \dfrac{x^2+4}{x(x-1)(x-2)} = \boxed{\dfrac ax + \dfrac b{x-1} + \dfrac c{x-2}}$

5(a). For some constants a-f,

$\dfrac{x^5+1}{(x^2-x)(x^4+2x^2+1)} = \dfrac{x^5+1}{x(x-1)(x+1)(x^2+1)^2} \\\\ = \dfrac{x^4 - x^3 + x^2 - x + 1}{x(x-1)(x^2+1)^2} = \boxed{\dfrac ax + \dfrac b{x-1} + \dfrac{cx+d}{x^2+1} + \dfrac{ex+f}{(x^2+1)^2}}$