What is the derivative of x^e?

1 Answer
Jan 31, 2016

d/dx x^e = ex^(e-1)

Explanation:

If k is a constant, then the power rule states that

d/dx x^k = kx^(k-1)

e is no different.

d/dx x^e = ex^(e-1)


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What follows is a short proof of the power rule for any real constant using implicit differentiation and the derivative d/dxln(x) = 1/x.

Let k in RR be constant, and let y = x^k

Then ln(y) = ln(x^k) = kln(x)

Differentiating, we have d/dxlny = d/dxkln(x)

=> 1/ydy/dx = k/x

=> dy/dx = ky/x = kx^k/x = kx^(k-1)

:. d/dxx^k = kx^(k-1)