I have solved the majority of the problem but I am stuck on step B !
Suppose that f(x)=8x^2+6x
(A) slope of tangent line = 70
(B)How do I find instantaneous rate of change for f(x) at x=4 ???
(C) Equation of tangent line y=70x-128

Question

anonymous · Answer

Isn't that just slope, so find the derivative and plug in 4? Sorry my brain is dead after work.

anonymous · Answer

No, the derivative of the f(x) so its 16x+6 => 16(4)+6 =>70. Could be wrong, its been a while for me.

anonymous · Answer

Oh never mind I was plugging in 4 to the wrong equation, but I didn't know that slope was instantaneous rate of change ! Thanks for the hint :D

anonymous · Answer

More like I forgot thanks though :)

anonymous · Answer

No problem I am currently in Calculus III and its been a while doing derivatives.

anonymous · Answer

Yeah I just started calculus :3