(a+b)^2=a^2+2ab+b^2;
(a-b)=a^2-2ab+b^2;
a) (с-х)^2=с^2-2сх+х^2;
б) (-с-4)^2=(-с)^2-2*4*(-с)+4^2=c^2+8c+16(
в) (6с+7)^2=(6с)^2+3*7*6с+7^2=36с^2+126с+49;
г) (5с-9х)^2=(5с)^2-2*5с*9х+(9х)^2=25с^2-90сх+81х;
д) (-с^2+3х^4)^2=(-с^2)^2-2*(-с^2)*3х^4+(3х^4)^2=с^4+6х^4*с^2+9х^8.
(a*b)^n=a^n*b^n;
(3*4)^2=12^2=144;
(3*4)^2=3^2*4^2=9*16=144.