How do you differentiate #v=(sqrtx+1/root3x)^2#?

1 Answer
Apr 19, 2018

#v'(x) = 1 + 1/3x^(-5/6) -2/3x^(-5/3)#

Explanation:

write both #x#-terms as numerical exponents of #x:#

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

#root3(x) = x^(1/3)#

#1/(root3(x)) = x^(-1/3)#

#(sqrt(x) + 1/(root3(x)))^2 = (x^(1/2) + x^(-1/3))^2#

using FOIL:

#(x^(1/2) + x^(-1/3))(x^(1/2) + x^(-1/3)) = x^1 + x^(1/6) + x^(1/6) + x^(-2/3)#

then you can differentiate these values separately, using the power rule

#f(x) = nx^(n-1)#.

when #x^n = x^1#, #nx^(n-1)# is #x^0#, or #1#.

when #x^n = x^(1/6)#, #nx^(n-1)# is #1/6x^(-5/6)#.

when #x^n = x^(-2/3)#, #nx^(n-1)# is #-2/3x^(-5/3)#.

hence, when #x^1 + x^(1/6) + x^(1/6) + x^(-2/3)# is differentiated, the result is

#1 + 1/6x^(-5/6) + 1/6x^(-5/6) + -2/3x^(-5/3)#.

this can be simplified to #1 + 1/3x^(-5/6) -2/3x^(-5/3)#.

or even #(3 + x^(-5/6) - 2x^(-5/3))/3#.

#v'(x) = 1 + 1/3x^(-5/6) -2/3x^(-5/3)#.