Nazlee R. answered • 12/03/20
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f'=18x-6
f'(-1)= 18(-1)-6
=-24
Nazlee R.
tutor
Ok let me show using f(x+h)-f(x)/h
9(x+h)^2-6(x+h) -(9x^2-6x)/h
9x^2+18xh+9h^2-6x-6h-9x^2+6x/h
We are left with
18xh +9h^2-6h/h
Factoring out the h,
18x+9h-6
Plug in (-1) for x and drop the h term since in
the limit h goes to zero,
-18-6=-24
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12/03/20
Lu J.
Don't you plug it into f(x+h)-f(x) /h to find derivative though?12/03/20