Question

If ( x – 5 ) ( x + 3 ) = x2 + ax -15, then the value of a is .... a) 3 b) – 5 c) - 2 d) 2 13​

Answer 1

Answer:

$(x-5)(x+3)=x ^ { 2 } +ax-15$

$x^{2}-2x-15=x^{2}+ax-15$

$x^{2}+ax-15=x^{2}-2x-15$

$ax - 15 = {x}^{2} - 2x - 15 - {x}^{2}$

$ax = - 2x - 15 + 15$

$ax = - 2x$

$\frac{xa}{x} = - \frac{2x}{x}$

$a = - \frac{2x}{x}$

$divide \: 2x \: by \: x$

$a = - 2$

So , we got value of a = -2