Question

calcueaza ac+bc+ad+bd stiind ca a+b=27 si c+d=30 (prin ab intelegam a x b)

Answer 1

ac+bc+ad+ad+bd=c(a+b)+d(a+b)=c·27+d·27=27·(c+d)=27·30=810   se dă factorul comun

Answer 2

ac+bc+ad+bd=ax(c+d)+bx(c+d)=(c+d)x(a+b)=30x27= 810