Question

Find the derivative of f(x) = -12x2 + 9x at x = 6.

Answer 1

do you know the power rule for finding a derivative?

Answer 2

if y = ax^n

y' = anx^(n-1)


this rule can be applied to -12x^2 and + 9x

Answer 3

for 12x^2 we have

a = -12 and n = 2

so to get the derivative of 12x^2 plug these values into the formula for y'

Answer 4

@welshfella thank you!

Answer 5

yw

Answer 6

so to set it up i would do y=-12(2)x^(2-1)?

Answer 7

where does the 9x come into play?

Answer 8

@welshfella

Answer 9

thats right for the derivative of -12x^2
this simplifies to -24x^1 = -24x

Answer 10

for 9x = 9x^1
a = 9 and n = 1

so derivative is 1*9 x^(1-1) = 9x^0

what is the values of x^0?

Answer 11

anything to the power 0 = 1 right?

so our derivative is 9

so we have f'(x) = -24x + 9