How do I find the answer?

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2 Answers
Jan 17, 2018

16(12x^2-1)16(12x21)

Explanation:

Differentiate twice! Using chain rule:

y = (4x^2 - 1)^2y=(4x21)2
(dy)/(dx) = 2 * (4x^2 - 1) * (8x) = 64x^3 - 16xdydx=2(4x21)(8x)=64x316x

Using power rule,
(d^2y)/(dx^2) = d/(dx) (dy)/(dx) = 192 x^2 - 16 = 16(12x^2-1) d2ydx2=ddxdydx=192x216=16(12x21)

Jan 17, 2018

Answer 'D' or (d^2y)/(dx^2)=16(12x^2-1)d2ydx2=16(12x21)

Explanation:

So to find the second order derivative we must differentiate it twice.

I would recommend multiplying out the brackets before doing the differential (it will make the algebra easier in the end)

y=(4x^2-1)^2=16x^4-8x^2+1y=(4x21)2=16x48x2+1

:. (dy)/(dx)=64x^3-16x

and (d^2y)/(dx^2)=192x^2-16

Factorising by 16 yields;

(d^2y)/(dx^2)=16(12x^2-1)