[질문] 곱셈공식3가지알려주세요

(a+b)제곱 = a제곱+2ab+b제곱 (a-b)제곱 = a제곱-2ab+b제곱 (x+a)(x+b) = x제곱+(a+b)x+ab (ax+b)(cx+d) = acx제곱+(ad+bc)x+bd (a+b)(a-b) = a제곱-b제곱