How do you use the definition of a derivative to find the derivative of f(x)= 2x^2-xf(x)=2x2x?

1 Answer
Jun 21, 2018

f'(x)=4x-1

Explanation:

"differentiating from "color(blue)"first principles"

f'(x)=lim_(hto0)(f(x+h)-f(x))/h

color(white)(f'(x))=lim_(hto0)(2(x+h)^2-(x+h)-(2x^2-x))/h

color(white)(f'(x))=lim_(hto0)(2x^2+4hx+2h^2-x-h-2x^2+x)/h

color(white)(f'(x))=lim_(hto0)(4hx+2h^2-h)/h

color(white)(f'(x))=lim_(hto0)(cancel(h)(4x+2h-1))/cancel(h)

color(white)(xxxx)=4x-1