find the hcf and lcm of the polynomial

4x2 - 36, 2x2 - 12x +18 and 2x2 + x -21

Factorize each of the following as

Now in each of the above  (x-3) is a common factor 

∴HCF= (x-3)

LCM= 4(x-3)(x+3)(x-3)(x+7)