Question

If one of the factor of x^2 + x - 20 is (x+5),find the other.
(a) x-4?
(b) x+2?
(c) x+4?
(d) x-5?

Answer 1

ANSWER-::Option a is correct i.e x-4

Let(x−a)

be the other factor.

Now,

(x+5),(x−a)

are factors of the quadratic equation

x 2x−20

Thus,

(x+5)(x−a)=x 2x−20

=>x 2ax+5x−5a

=x 2x−20

=>x(5−a)−5)

=x−20

Now, considering the co-efficients of

xon the both sides,

5−a=1

=>a=5−1

=4

Therefore the other factor is

Therefore the other factor is(x−4)