If the solutions to to the equation (x+a)(x+b) = 0 are x=6 and x= -4, then a + b = ?
Your choices are: A) -24
B) -12
C) -2
D) 2
E) 24
Explanation would be nice as well. Thanks!
2007-10-09 08:22:04 · 4 answers · asked by Petree33 2 in Science & Mathematics ➔ Mathematics
yea i got it once i looked at it a bit longer, but thanks to everyone who gave an answer.
2007-10-09 08:45:46 · update #1
If the solutions are x = -4 and x = 6, that means the equation is
(x - 6)(x + 4) = 0
So... a = -6 and b = 4 (or vice versa).
So...
-6 + 4 = -2
2007-10-09 08:30:29 · answer #1 · answered by Mathematica 7 · 0⤊ 0⤋
C) -2
The reason is that the solutions are the numbers that will make the equation 0. To make it 0, set each of the parentheses equal to 0, since anything times 0, is 0. So, if you have x + a = 0... sub in 6... 6 + a = 0. a = -6. Sub in x = -4 and you get -4 + b = 0 ...... b = 4. -6 + 4 = -2
2007-10-09 15:30:28 · answer #2 · answered by Anonymous · 0⤊ 0⤋
C) -2
multiple out the equation:
x^2 +bx+ax+ab = 0
substitute x=6:
36+6b+6a+ab=0
substitute x=-4:
16-4b-4a+ab=0
subtract these equations:
20+10b+10a=0
reduce:
2+b+a=0, then a+b=-2
2007-10-09 15:37:25 · answer #3 · answered by revo 2 · 0⤊ 0⤋
C
2007-10-09 15:31:40 · answer #4 · answered by gebobs 6 · 0⤊ 0⤋