2007-05-10 12:10:15 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
First factor out 4
4x² + 32x - 80 = 0
4(x² + 8x - 20) = 0
Then factor (x² + 8x - 20) into (x+a)(x+b) where a and b are such that
ab = -20
a + b = 8
=> a = 10, b = -2
4(x + 10)(x - 2) = 0
=> solutions: x = -10, x = 2
Hope this helps.
2007-05-10 12:12:44 · answer #1 · answered by M 6 · 6⤊ 0⤋
4x^2 + 32x - 80 = 0
4(x^2 + 8x - 20) = 0
4(x + 10) (x - 2) = 0
x = -5/2 T
or
x = 1/2 F
2007-05-10 19:27:50 · answer #2 · answered by Anonymous · 0⤊ 0⤋
4x^2+32x-80=0
to factor
(4x-8)(x+10)=0
*4x-8= 0
+8 +8
4x=8
*divide both sides by 4
so x=2
**then...
x+10=0
-10 -10
so x=-10
*** so your answer will be...
x=2 or x=-10
** you'll have 2 answers for x
2007-05-10 19:23:15 · answer #3 · answered by mikage2590 1 · 0⤊ 0⤋
x² + 8x - 20 = 0
(x + 10).(x - 2) = 0
x = -10 , x = 2
2007-05-11 10:43:43 · answer #4 · answered by Como 7 · 0⤊ 0⤋
Do like she said above an then look at the factors
you end up with 4(x-2)(x+10)
2007-05-10 19:16:18 · answer #5 · answered by Tom M 3 · 0⤊ 0⤋
we can change this equation to:
x^2 + 8x - 20 = 0
==>
(x+10)(x-2)=0
2007-05-10 19:16:55 · answer #6 · answered by Farid 1 · 0⤊ 0⤋
4(x^2+8x-20)=0
4(x+10)(x-2)=0
x=-10 or x=2
2007-05-10 19:15:00 · answer #7 · answered by Dave aka Spider Monkey 7 · 0⤊ 0⤋