Question

9a^{2}+4b^{2}+16c^{2}+12ac-16bc-24ca solution steps

Answer 1

(3a)²+(2b)²+(-4c)²+2(3a)(2b)+2(2b)(-4c)+2(-4c)(3a)
using formula a²+b²+ c²+2ab+2bc+2ca = (a+b+c)²
then,
(3a)²+(2b)²+(-4c)²+2(3a)(2b)+2(2b)(-4c)+2(-4c)(3a)= [3a+2b+(-4c)]²= (3a+2b-4c)²
hope this helps

Answer 2

(3a)²+(2b)²+(-4c)²+2(3a)(2b)+2(2b)(-4c)+2(-4c)(3a)
using formula a²+b²+ c²+2ab+2bc+2ca = (a+b+c)²
then, 
(3a)²+(2b)²+(-4c)²+2(3a)(2b)+2(2b)(-4c)+2(-4c)(3a)= [3a+2b+(-4c)]²= (3a+2b-4c)²  
(3a+2b-4c)²