Question

5. Find the HCF and LCM of: (d) x²+x-20 and x² + 9x +20​

Answer 1

First factorise both expressions:

X^2 + x - 20 = (x - 4)(x + 5)
X^2 + 9x + 20 = (x + 4)(x + 5)

So the HCF = x + 5
And the
LCM = (x - 4(x+ 4)(x + 5)
= (x^2 - 16)(x +’5)
= x^3 + 5x^2 - 16x - 80