Since the diameter of the cylinder is 10, its radius is half that, or 5, thus
Slope formula is
m = (y2 - y1)/(x2 - x1)
A. m = (5 - 0)/(-2 + 2)
m = (5)/(0)
m = error
B. m = (-2 - 0)/(0 + 2)
m = (-2)/(2)
m = -1
C. m = (2 - 0)/(2 - 0)
m = (2)/(2)
m = 1
D. m = (0 - 0)/(2 - 3)
m = (0)/(-1)
m = 0
the undefined slope would be the one that came out as error, so A

We're dividing fractions, so we will flip the one in the denominator upside down and we will multiply it with the numerator.

Let's equal this too 8/x

Cross multiply.

Divide both sides by 15.
The derivative of
at a point
in the direction of a vector
is

We have

and

Then the derivative at
in the direction of
is

Plug in 3 for y
8(3)^2-(3)-8
8(9)-3-8
72-3-8 = 61