If F(x)=x^2+1 when F(x)=(a-1)

**shirania** · July 12th 2012, 04:15 PM

I had this question on a state test... what do you guys think it is?? Its been years since I've done math and was kinda mad when i received this question because it showed me how much i'd forgotten

If your answer matches something below, show your work please to me and tell me i should go back to school, Thanks guys

choices were
A.) a^2
B.) a^2+2
C.) a^2-2a
D.) a^2+2a
E.) a^2-2a +2

**Reckoner** · July 12th 2012, 06:27 PM

Originally Posted by shirania

If $F(x)=x^2+1$ when $F(x)=(a-1)$

I have no idea what this is supposed to mean. Could you post the question exactly as it was worded? Or explain what it was asking you to find?

Edit: Looking at the answers, I'm guessing you were asked to evaluate $F(a-1)?$

In that case,

$F(x) = x^2 + 1$

$\Rightarrow F(a-1) = (a-1)^2 + 1$

Now expand and collect like terms.

**shirania** · July 12th 2012, 06:43 PM

the quest was
"If f(x)=x^2+1, then f(a-1)= what?" wanna say that is basically how it was worded.

(a-1)^2+1 is a^2-2a+3? right
so that would make the answers invalid??

**Reckoner** · July 12th 2012, 06:47 PM

Originally Posted by shirania

the quest was
"If f(x)=x^2+1, then f(a-1)= what?" wanna say that is basically how it was worded.

(a-1)^2+1 is a^2-2a+3? right
so that would make the answers invalid??

I don't know where you are getting the three from.

$f(a-1) = (a-1)^2 + 1$

$= (a-1)(a-1) + 1$

$= a^2 - 1a - 1a + 1^2 + 1$

$= a^2 - 2a + 2$

**shirania** · July 12th 2012, 06:49 PM

... BECAUSE i'm FREAKING STUPID.... LOL HAHAHHAHAHAHA 1^2 whole time i've been doing 1+1 in my head lol hahahahhaha wow i'm amazing... thanks bro lol lol

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