Hey guys, I'm using the definition of derivative to find f'(a), this always makes a mess. This is what I have done so far;
Question: f(t) = 2t3+t, find f'(a).
lim f(a+h)-f(a)/(h) - the formula
Here's all the foiling etc I did on the side:
eventually getting....2(a3+3a2h+3ah2+h3) = 2a3+6a2h+6ah2+2h3
so now I have,
6a2(0)+6a(0)2+2(0)3-1 = -1
f'(a) = -1?
Not sure where I went wrong, the derivative of 2t3+t is definitely not -1. Could use some guidance.
Ok so I figured out that I missed a step, after
I should have isolated h so I get
lim h(6a2+6ah+2h2-1)/h (now cancel out the h's)
= 6a2+1 how does this look?