How do you find the derivative of ln(x+sqrt((x^2)-1))?

1 Answer
Jul 28, 2016

1/sqrt(x^2-1)

Explanation:

d/dx ln(x+sqrt(x^2-1)) = 1/[x+sqrt(x^2-1)] * d/dx(x+sqrt(x^2-1)) (Standard differential and Chain rule)

= 1/[x+sqrt(x^2-1)] * (1 + 1/2(x^2-1)^(-1/2) * d/dx(x^2-1))
(Power rule and Chain rule)

= 1/[x+sqrt(x^2-1)] * (1 + 1/2(x^2-1)^(-1/2) * 2x)

= 1/[x+sqrt(x^2-1)] (1+ (cancel(2)x)/(cancel(2)sqrt(x^2-1)))

= 1/[x+sqrt(x^2-1)] ((sqrt(x^2-1) +x)/sqrt(x^2-1))

= 1/[cancel(x+sqrt(x^2-1))] ((cancel(x+ sqrt(x^2-1)))/sqrt(x^2-1))

= 1/(sqrt(x^2-1))