SOLUTION: Find the value of f′(x) at the given value of x. a) f(x) = 3x - 4√x,x = 4 b) f(x) = (x-4)(x+3),x = 3

Algebra ->  Test -> SOLUTION: Find the value of f′(x) at the given value of x. a) f(x) = 3x - 4√x,x = 4 b) f(x) = (x-4)(x+3),x = 3      Log On


   

Question 1190554: Find the value of f′(x) at the given value of x.
a) f(x) = 3x - 4√x,x = 4
b) f(x) = (x-4)(x+3),x = 3
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
you are simply replacing the x in f(x) with the value of x.

a.
f(x) = 3x - 4 * sqrt(x).
f(4) = 3 * 4 - 4 * sqrt(4) = 12 - 2 = 10

b.
f(x) = (x-4) * (x+3).
f(3) = (3-4) * (3+3) = -1 * 9 = -9

let me know if you have any questions.
theo