What is the derivative of sqrt(2x)2x ?

2 Answers
Mar 26, 2017

d/(dx) sqrt(2x) = sqrt(2)/(2sqrt(x))ddx2x=22x

Explanation:

For any non-zero power pp of xx we have:

d/(dx) x^p = p x^(p-1)ddxxp=pxp1

So:

d/(dx) sqrt(2x) = d/(dx) sqrt(2)sqrt(x)ddx2x=ddx2x

color(white)(d/(dx) sqrt(2x)) = d/(dx) sqrt(2)x^(1/2)ddx2x=ddx2x12

color(white)(d/(dx) sqrt(2x)) = sqrt(2)*1/2x^(-1/2)ddx2x=212x12

color(white)(d/(dx) sqrt(2x)) = sqrt(2)/2*1/x^(1/2)ddx2x=221x12

color(white)(d/(dx) sqrt(2x)) = sqrt(2)/2*1/sqrt(x)ddx2x=221x

color(white)(d/(dx) sqrt(2x)) = sqrt(2)/(2sqrt(x))ddx2x=22x

Mar 26, 2017

d/(dx) sqrt(2x) = sqrt(2)/(2sqrt(x))ddx2x=22x

Explanation:

Here is how to find it using the limit definition of derivative...

d/(dx) sqrt(2x) = lim_(h->0) (sqrt(2(x+h))-sqrt(2x))/h

color(white)(d/(dx) sqrt(2x)) = lim_(h->0) ((sqrt(2(x+h))-sqrt(2x))(sqrt(2(x+h))+sqrt(2x)))/(h(sqrt(2(x+h))+sqrt(2x)))

color(white)(d/(dx) sqrt(2x)) = lim_(h->0) ((sqrt(2(x+h)))^2-(sqrt(2x))^2)/(h(sqrt(2(x+h))+sqrt(2x)))

color(white)(d/(dx) sqrt(2x)) = lim_(h->0) (2(x+h)-2x)/(h(sqrt(2(x+h))+sqrt(2x)))

color(white)(d/(dx) sqrt(2x)) = lim_(h->0) (2color(red)(cancel(color(black)(h))))/(color(red)(cancel(color(black)(h)))(sqrt(2(x+h))+sqrt(2x)))

color(white)(d/(dx) sqrt(2x)) = lim_(h->0) 2/(sqrt(2(x+h))+sqrt(2x))

color(white)(d/(dx) sqrt(2x)) = 2/(sqrt(2(x+0))+sqrt(2x))

color(white)(d/(dx) sqrt(2x)) = 1/(sqrt(2x))

color(white)(d/(dx) sqrt(2x)) = sqrt(2)/(2sqrt(x))