Question

Factor x^3+2x^2-9x-18 , given that -2 is a zero.

Answer 1

(x + 2)(x + 3)(x - 3)

Explanation:

Given that x = - 2 is a zero then (x + 2) is a factor

Dividing x³ + 2x² - 9x - 18 by (x + 2) gives

x³ + 2x² - 9x - 18 = (x + 2)(x² - 9) = (x + 2)(x + 3)(x - 3)

Answer 2

x

3

+

2

x

2

+

9

x

+

18

x3+2x2+9x+18

Factor out the greatest common factor from each group.

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x

2

(

x

+

2

)

+

9

(

x

+

2

)

x2(x+2)+9(x+2)

Factor the polynomial by factoring out the greatest common factor,

x

+

2

x+2

.

(

x

+

2

)

(

x

2

+

9

)

(x+2)(x2+9)

Explanation: