Question

Find f(3) and f'(3), assuming that the tangent line to y = f(x) at a = 3 has equation
y = 6x + 8

Answer 1

the slope of the tangent line equals the derivative at the point x=3
-> f'(3) = 6

at x=3 both f(x) and the tangent line share the same point
y = 6(3) +8 = 26
-> f(3) = 26

Answer 2

so f ' (3) would be what? 1?

Answer 3

f(x) = 6x + 8 then f ' (x) = 6

so the gradient is a constant value.... m = 6....

find f(3) = 6 x 3 + 8 f(3) 26 f(-3) = 6 x (-3) + 8 f(-3) = -10

so you need to find 2 lines m = 6 point (3, 26) and m = 6 point (-3, -10)