x^2 +2x-6, how do you find the sum and roots for this equation?
2007-04-25 04:03:21 · 4 answers · asked by kushkosh 2 in Science & Mathematics ➔ Mathematics
in ax² + bx + c = 0, the sum of the roots = -b/a and the product of the roots = c/a
2007-04-25 04:10:51 · answer #1 · answered by Kathleen K 7 · 0⤊ 0⤋
If the roots are a and b, the equation is
(x - a)(x - b) = 0
(x - a)x - (x - a)b = 0
x^2 - ax - bx + ab = 0
x^2 - (a + b)x + ab = 0
-(a + b) = 2 ===> a+b = -2 in other words -2 is the sum of roots.
ab =-6 meaning that -6 is their products.
2007-04-25 11:10:25 · answer #2 · answered by Amit Y 5 · 0⤊ 1⤋
x^2 +2x - 6
= x^2 - (-2)x + (-6)
[(x-a)(x-b) = x^2 - (a+b)x +ab]
therefore, (a+b) = -2
and, ab = -6
2007-04-25 11:20:26 · answer #3 · answered by absentmindednik 3 · 0⤊ 0⤋
Without going through the trouble of solving it
This can be written
(x-a)*(x-b) = x^2 - (a+b)x + ab
So a+b = -2
ab = -6
2007-04-25 11:08:25 · answer #4 · answered by Dr D 7 · 0⤊ 1⤋