Factoring x^3-2x^2-9?
回答 (4)
2008-09-17 3:30 pm
✔ 最佳答案
x^3 - 2x^2 - 9= x^3 - 3x^2 + x^2 - 3x + 3x - 9
= (x^3 - 3x^2) + (x^2 - 3x) + (3x - 9)
= x^2(x - 3) + x(x - 3) + 3(x - 3)
= (x^2 + x + 3)(x - 3)
2008-09-17 3:34 pm
(X - 3) (X + 0.5 + aj) (X + 5 - aj), where a = sqrt (2.75)
2008-09-17 3:31 pm
group the terms and take out the common factor first
x^2(x-2)-9
(x^2-9)(x-2)
which can be rewritten as
(x^2+0x-9)(x-2)
now, simplify the first bracket by splitting the middle term.
(x^2+3x-3x-9)(x-2)
x(x+3)-3(x+3)(x+2)
the final answer is (x+3)(x-3)(x+2)
glad to help frosted muffin.
x^2(x-2)-9
(x^2-9)(x-2)
which can be rewritten as
(x^2+0x-9)(x-2)
now, simplify the first bracket by splitting the middle term.
(x^2+3x-3x-9)(x-2)
x(x+3)-3(x+3)(x+2)
the final answer is (x+3)(x-3)(x+2)
glad to help frosted muffin.
2008-09-17 3:29 pm
Since you can't factor by looking at the common factors or using quadratic equation, you just use good old algebra to solve the problem.
x^3 - 2x^2 - 9 = 0
x^3 - 2x^2 = 9
x^2*(x - 2) = 9
Here, you break the equation into 2 parts: x^2 = 9 , and x-2 = 9.
x^2 = 9
x = +3, -3
x-2 = 9
x = 11
So the answers are x=-3, 3, 11.
Hope that helps!
x^3 - 2x^2 - 9 = 0
x^3 - 2x^2 = 9
x^2*(x - 2) = 9
Here, you break the equation into 2 parts: x^2 = 9 , and x-2 = 9.
x^2 = 9
x = +3, -3
x-2 = 9
x = 11
So the answers are x=-3, 3, 11.
Hope that helps!
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