Question

Which shows the factored form of x2 – 12x – 45?

(x + 3)(x – 15)
(x – 3)(x – 15)
(x + 3)(x + 15)
(x – 3)(x + 15)

Answer 1

$Given \: Quadratic \: expression : \\x^{2} - 12x - 45$

/* Splitting the middle term, we get */

$= x^{2} +3x - 15x - 45 \\= x( x + 3 ) - 15( x + 3 ) \\= ( x + 3 )( x - 15 )$

Therefore.,

$\red { Factors \: of \: x^{2} - 12x + 3}$

$\green { = ( x + 3 )( x - 15 )}$

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