Question

Factor: 5x2 – 15x – 20.

(a) 5(x-4)(x+1),
(b) -2(x-4)(x+5),
(c) -5(x+4)(x-1),
(d) 5(x+4)(x+1).

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Answer 1

Answer;

5(x+1)(x-4)

Explanation:

$5x {}^{2} - 15x - 20$

=>Factor out 5 from the expression

$5(x {}^{2} - 3x - 4)$

=> Write -3x as a difference

$5(x {}^{2} + x - 4x - 4)$

=> Factor out X from the expression

$5(x \times(x + 1) - 4x - 4)$

=> Factor out -4 from the expression

$5(x \times (x + 1) - 4(x + 1))$

=> Factor out (x+1) from the expression

$5(x + 1)(x - 4)$

Solved √

Answer 2

$5 {x}^{2} - 15x - 2 \\ = 5( {x}^{2} - 3x - 4) \\ = 5( {x}^{2} - 4x + 1x - 4) \\ = 5(x(x - 4) + 1(x - 4)) \\ = 5(x - 4)(x + 1)$

option A is your right answer