# basic algebra help!

• Jan 5th 2010, 10:42 AM
mike--1988
basic algebra help!
this is a simple question but its confused me
heres the question

f(x)= 2 - x^2 where x = -3

is it -7 or is it 11 im confused by the sign change

thanks..
• Jan 5th 2010, 10:46 AM
shinhidora
Quote:

Originally Posted by mike--1988
this is a simple question but its confused me
heres the question

f(x)= 2 - x^2 where x = -3

is it -7 or is it 11 im confused by the sign change

thanks..

$f(x) = 2 - x^2$ where $x = -3$
$f(x) = 2-(-3)^2$
$f(x) = 2 - 9$
$f(x) = -7$
• Jan 5th 2010, 10:46 AM
$3(3)=3+3+3=9$

$3(-3)=-3-3-3=-9$

$(-3)(-3)=-[3(-3)]=opposite\ of\ subtract\ 3\ three\ times$

$which\ is\ add\ 3\ three\ times.$

$Hence\ (-3)(-3)=3(3)=9$

$2-x^2=2-(-3)^2=2-(9)=-7$
• Jan 5th 2010, 10:47 AM
bigwave
Quote:

Originally Posted by mike--1988
this is a simple question but its confused me
heres the question

f(x)= 2 - x^2 where x = -3

is it -7 or is it 11 im confused by the sign change

thanks..

f(-3) = 2 -(-3)^2 = -7
• Jan 5th 2010, 10:52 AM
mike--1988
thanks everyone (Rock)