if y=x^2+5x-9 what will the y value be if x = -2

is it -23 or -15 ? so i guess is -2^2 different from (-2)^2

Question

if y=x^2+5x-9 what will the y value be if x = -2

is it -23   or   -15  ?     so i guess is -2^2 different from (-2)^2

anonymous · Answer

$$ (-2)^2 = (-1)^2(2)^2 = 1 * 4 = 4$$  :)

anonymous · Answer

$$ \textrm{but remember that} \  (-1)^n \ \textrm{is only positive when n is an even number} 
\ \ 
\ (-1)^1 = -1
\ (-1)^2 = 1
\ (-1)^3 = -1
\ (-1)^4 = 1
\ \textrm{etc...}$$

anonymous · Answer

so if $$y= x^2+5x+6   $$  and -4>= x >=0 then (-4,2) (-3,0)(-2,0)(-1,2)(0,6)  right ?

anonymous · Answer

Your domain doesn't really make sense... but all of those points are on that parabola :)

anonymous · Answer

did you mean-4 ≥x ≤ 0 ?

anonymous · Answer

yes, thanks. I need to watch that !!!!

anonymous · Answer

Thanks! And the ≤ and ≥ are always a pain :P

anonymous · Answer

yes, not only that but even when i get an equation out that looks like it was designed by a rocket scientist, I plough through and impress myself except if I have to take a positive number to the other side, i make it stay positive....every time!!!! nearly :)

anonymous · Answer

then you have to go back like 50,000 steps trying to figure out where it happened?  Yah, been there >.>  At least you recognize it though! :D

anonymous · Answer

And kudos on plowing through rocket science! ^^

anonymous · Answer

haaa.. yes, its tough when you look at an equation and you have to get rid of squares,roots brackets negative powers and stuff flying every which way but I see a +3 in there somewhere, and I say to myself, I'm defiantly going to screw this up !!! haaa :) thanks for helping with the question. I just liked the look of the graph that was wrong better so I became unsure :)

anonymous · Answer

Anytime ^^