Answer:
(x-3), 4 (x - 3)^2 (x + 3) (2 x + 7)
Explanation:
Factor all the expressions,
1st expression= 4x^2 - 36=4(x^2-9)=4(x+3)(x-3)
2nd expression=2x^2 - 12x + 18 =2(x^2-6x+9)=2 (x - 3)^2=2(x-3)(x-3)
3rd expression=2x^2 + x - 21=(x - 3) (2 x + 7)
HCF=Commo factor=(x-3)
LCF=Common factor*Remaining factor=4(x+3)(x-3)(x-3) (2 x + 7)=4 (x - 3)^2 (x + 3) (2 x + 7)