Question

.If one of the factor of x^2 + x – 20 is (x + 5). Find the other​

Answer 1

Answer: (x-4)

Step-by-step explanation:

Let (x−a) be the other factor.

Now, (x+5),(x−a) are factors of the quadratic equation x^2 +x−20

Thus,

(x+5)(x−a)=x^2 +x−20

=>x^2 −ax+5x−5a=x^2+x-20  

=>x(5−a)−5a=x−20

Now, considering the co-efficients of x on the both sides,

5−a=1

=>a=5−1=4

Therefore the other factor is (x−4)