[질문] x제곱+4(a+b)x+3a제곱+6ab+3b제곱을인수분해하여라

x²+4(a+b)x+3a²+6ab+3b²= x²+4(a+b)x+3(a²+2ab+b²) = x²+4(a+b)x+3(a+b)^2= (x+a+b)(x+3a+3b)