Evaluate the limit lim_(h rarr 0) {(x-h)^3-x^3}/h?
1 Answer
Sep 14, 2017
lim_(h rarr 0) {(x-h)^3-x^3}/h = -3x^2
Explanation:
We seek:
L = lim_(h rarr 0) {(x-h)^3-x^3}/h
Therefore:
L = lim_(h rarr 0) {x^3-3x^2h+3xh^2-h^3-x^3}/h
\ \ \ = lim_(h rarr 0){-3x^2h+3xh^2-h^3}/h
\ \ \ = lim_(h rarr 0)-3x^2+3xh-h^2
\ \ \ = -3x^2 +0 + 0
\ \ \ = -3x^2