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by ST » Fri Jun 12, 2009 6:10 am
If (t-8) is a factor of t^2 - kt - 48, then k =

a. -6
b. -2
c. 2
d. 6
e. 14

answer is C

could someone explain this? I do not like the explanation in the book and having hard time to understand it. Thanks
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by deagez » Fri Jun 12, 2009 6:22 am
the way I saw this is to factor this out to (t+6)(t-8)

multiply this back up again and you get t^2-2t-48

so the k is 2.
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by deagez » Fri Jun 12, 2009 6:28 am
I guess what brought me to start the problem off this way, is the 8 in (t-8),,,so my next thought is what multiplied by 8 would be a negative 48?

6 right? so that is how I decided to do (t-8)(t+6) and see what the middle factor "k" would be
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by tohellandback » Fri Jun 12, 2009 6:30 am
t-8 is a factor
just put t=8 in the eq and it should be 0
t^2 - kt - 48
8^2-k*8-48=0
16-8k=0
k=2
The powers of two are bloody impolite!!
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by ST » Fri Jun 12, 2009 6:42 am
I like these explanation. pretty starighforward then explanation in 10th edition.
Thank you
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