Posted by kajal on .
Find the following limit where f(x) = 4x2 − 3x.
limit
delta x > f(x + delta x) f(x)/delta x
can someone please help me

calculus 
Steve,
I assume you mean the limit as delta x > 0.
I'll use delta x = h for simplicity
(f(x + h)  f(x))/h
= (4(x+h)^2  3(x+h)  (4x^2  3x))/h
= (4x^2 + 8xh + 4h^2  3x  3h  4x^2 + 3x)/h
= (8xh + 4h^2  3h)/h
= 8x  3 + 4h
Limit as h>0 = 8x3
Looks like the derivative, eh?