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Topic: [ap-calculus] Need help plaease on 2008 BC MC # 17
Replies: 3   Last Post: Sep 21, 2012 12:18 AM

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 Wilder Bob Posts: 406 Registered: 2/1/08
RE:[ap-calculus] Need help plaease on 2008 BC MC # 17
Posted: Sep 20, 2012 7:15 PM

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Hi - it's not multiplication, it's composition of functions. Multiplication of two functions would require at a minimum h(x)(x^2-3).

So ... use the chain rule!

Bob Wilder
Middletown High School
________________________________________
From: Qayumi, Enayat [eqayumi@tusd.net]
Sent: Thursday, September 20, 2012 1:18 PM
To: AP Calculus
Subject: [ap-calculus] Need help plaease on 2008 BC MC # 17
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If h is a differentiable function and f(x) = h (x^2 - 3)

Why is the f'(x) = 2x h'(x^2-3) which will give the correct answer once you plug in x = 2

And Not

f'(x) = h' (x^2 - 3) + h (2x) due to the product rule? Once you find f'(2) = h' + 4h, it is not one of the MC options.