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November 13th, 2016, 01:20 PM   #1
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Another functional disfunction

If r(t) = 2t+3 and s(t) = 7t^2 - t find :-

s(r(t))
s(r(t)) = s(2t + 3) = 7(2t + 3)^2 − (2t + 3) <<<{Where is this guy coming from?}

= 7(4t^2 + 12t + 9) − (2t + 3)

= (28t^2 + 84t + 63) − (2t + 3)
= 28t^2 + 82t + 60

I can understand the first (2t + 3)^2 but surely that should cover the function s. Why the need for the -2t + 3?

Last edited by Kevineamon; November 13th, 2016 at 01:23 PM.
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November 13th, 2016, 01:53 PM   #2
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Each "t" in "s(t) = 7t^2 - t" is to be replaced with "2t + 3".
Thanks from Kevineamon
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November 13th, 2016, 02:03 PM   #3
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Ahhh well there we go. Thanks Skipjack.
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