Question

$6)100b^{2}+9c^{2}-60bc 7)9y^{4}+36y^{2}z+4z^{2} 8)72yt+81y^{2}+16t^{2}$

Answer 1

6)=(10b-3c)^2;
7)=(3y^2+3z)^2;
8)=(9y+4t)^2