How do you differentiate y=csc^-1(4x^2)y=csc1(4x2)?

1 Answer
Nov 12, 2016

dy/dx=(-2)/(xsqrt(16x^4 - 1)) (=(-2)/(xsqrt((4x^2+1)(4x^2-1)))) dydx=2x16x41(=2x(4x2+1)(4x21))

Explanation:

y=csc^-1(4x^2) <=> cscy=4x^2y=csc1(4x2)cscy=4x2

Differentiating implicitly we have:
cscy=4x^2 cscy=4x2
-cscycotydy/dx=8x cscycotydydx=8x
-(4x^2)cotydy/dx=8x (4x2)cotydydx=8x
cotydy/dx=-2/x cotydydx=2x ..... [1]

Now 1 + cot^2A -= csc^2A 1+cot2Acsc2A
:. 1 + cot^2y = 16x^4
:. cot^2y = 16x^4 - 1
:. coty = sqrt(16x^4 - 1)

Substituting into [1] we get:
sqrt(16x^4 - 1)dy/dx=-2/x

:. dy/dx=(-2/x)/sqrt(16x^4 - 1)
:. dy/dx=(-2)/(xsqrt(16x^4 - 1)) (=(-2)/(xsqrt((4x^2+1)(4x^2-1))))