How exactly is this happening? I was studying Derivative and my book says if: y = <msqrt

Kassandra Ross

Kassandra Ross

Answered question

2022-06-12

How exactly is this happening?
I was studying Derivative and my book says if:
y = ( 1 + x 2 ) 3
Then its derivative is:
y = 3 ( 2 x ) ( 1 + x 2 ) 2 2 ( 1 + x 2 ) 1 = 3 x ( 1 + x 2 )
I can't understand how the writer has changed the first derivative fraction into the second one. In other words, how did he simplify?
Note: I'm really really basic, so please explain in details.
Thank you.

Answer & Explanation

humusen6p

humusen6p

Beginner2022-06-13Added 22 answers

Observe that
( 1 + x 2 ) 3 = ( 1 + x 2 ) 3 / 2
Thus
( ( 1 + x 2 ) 3 / 2 ) = 3 2 ( 1 + x 2 ) 3 / 2 1 ( 1 + x 2 ) = 3 2 ( 1 + x 2 ) 1 / 2 2 x = 3 2 ( 1 + x 2 ) 1 / 2 2 x = 3 x 1 + x 2
The first equation is due to the chain rule. i.e.
( f ( g ( x ) ) ) = f ( g ( x ) ) g ( x )
with f ( x ) = x 3 / 2 and g ( x ) = ( 1 + x 2 )

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