F(x) = 3x + x3 x > 0
a) Differentiate to find f'(x)
Given that f'(x) = 15,
b) Find the value of x

Please check the explanation.

Step-by-step explanation:

Given

f(x) = 3x + x³

Taking differentiate

solving

now solving

Thus, the expression becomes

Thus,

f'(x) = 3 + 3x²

Given that f'(x) = 15

substituting the value  f'(x) = 15 in f'(x) = 3 + 3x²

f'(x) = 3 + 3x²

15 =  3 + 3x²

switch sides

3 + 3x² = 15

3x² = 15-3

3x² = 12

Divide both sides by 3

x² = 4

Thus, the value of x will be:

7.3

step-by-step explanation:

step-by-step explanation:

points a and b are equidistant from the desired line, so the line you find by using them will go through point r.

using points other than a and b will give the desired line only if they are equidistant from r. if they are randomly located, the perpendicular line you create will not necessarily go through point r, hence will not be a solution to the problem.