Answer:
7
Step-by-step explanation:
5(x - 3) = 2(x + 3) Distribute
5x - 15 = 2x + 6
+ 15 + 15 Switch sides to the liked terms
5x = 2x + 6 + 15
-2x -2x Switch sides to the liked terms
5x - 2x = 6 + 15
<u>3x</u> = 21 Divide
3 3
x = 7
Answer:



Step-by-step explanation:
<u>Optimizing With Derivatives
</u>
The procedure to optimize a function (find its maximum or minimum) consists in
:
- Produce a function which depends on only one variable
- Compute the first derivative and set it equal to 0
- Find the values for the variable, called critical points
- Compute the second derivative
- Evaluate the second derivative in the critical points. If it results positive, the critical point is a minimum, if it's negative, the critical point is a maximum
We know a cylinder has a volume of 4
. The volume of a cylinder is given by

Equating it to 4

Let's solve for h

A cylinder with an open-top has only one circle as the shape of the lid and has a lateral area computed as a rectangle of height h and base equal to the length of a circle. Thus, the total area of the material to make the cylinder is

Replacing the formula of h

Simplifying

We have the function of the area in terms of one variable. Now we compute the first derivative and equal it to zero

Rearranging

Solving for r

![\displaystyle r=\sqrt[3]{\frac{4}{\pi }}\approx 1.084\ feet](https://tex.z-dn.net/?f=%5Cdisplaystyle%20r%3D%5Csqrt%5B3%5D%7B%5Cfrac%7B4%7D%7B%5Cpi%20%7D%7D%5Capprox%201.084%5C%20feet)
Computing h

We can see the height and the radius are of the same size. We check if the critical point is a maximum or a minimum by computing the second derivative

We can see it will be always positive regardless of the value of r (assumed positive too), so the critical point is a minimum.
The minimum area is


Just did a specific one of these; let's do the general case.
The point nearest the origin is (a,b).
The line from the origin through the point is

The line we seek is perpendicular to this one. We swap the coefficients on x and y, negating one, to get the perpendicular family of lines. We set the constant by plugging in the point (a,b):


That's standard form; let's plug in the numbers:


Should be a scale factor of y= 1/9
You can factor (x^3 and 6x^2) and (-4x and -24).
So x^2(x+6) - 4(x+6)
(x^2-4)(x+6)
(x-2)(x+2)(x+6)