solve by factoring x^2+8x=20?
Can anyone show me how to do this, i'm struggling!

Question

solve by factoring x^2+8x=20?
Can anyone show me how to do this, i'm struggling!

anonymous · Answer

i know x=4, but i don't remember how to work this?

anonymous · Answer

good to know you'restruggling eith a question......
x^2+8x-20=0
x^2+10x -2x-20=0
x(x+10)-2(x+10)=0
(x+10)(x-2)+0
x=-10 or 2

anonymous · Answer

x=2*

anonymous · Answer

its=0

anonymous · Answer

not+0

anonymous · Answer

Ohh okay, i see what i was doing wrong,
thanks(:
Would you mind helping with one more?

anonymous · Answer

@Meinme

anonymous · Answer

yeah feel free

anonymous · Answer

Okay, this one is:
Solve by quadratic formula 5x^2 + 2x - 7 = 0

anonymous · Answer

b^2-4ac= 4+140=144

by quadratic formula we have |dw:1362693495342:dw|

anonymous · Answer

ans is 1 or -1.4

anonymous · Answer

wait, how do you know to put -2 +- sqrt 144 over 10? @meinme

anonymous · Answer

its formula

anonymous · Answer

okay, i just dont understand how you get those numbers, from the numbers i gave you?
does that make sense,

anonymous · Answer

yeah do u know the formula of finding x in quadratic?

anonymous · Answer

yes

anonymous · Answer

{-b+-sqrt(b^2-4ac}/2a

anonymous · Answer

right, so how do you determine which is a, b, and c...

anonymous · Answer

general quadratic equation is ax^2+bx+c=0 now compare your equation youll get a, b and c

anonymous · Answer

Ohh, okaay, i see. Thank you so much.