Question

simplify (a+b)(c-d)+(c-b)(c+d)+2(ac+bd)

Answer 1

(a+b)(c-d)+(a-b)(c+d)+2(ac+bd)

now we multiply each other,

      =a(c-d)+b(c-d)+a(c+d)-b(c+d)+2(ac+bd)

          =ac-ad+bc-bd+ac+ad-bc-bd+2ac+2bd

             =2ac-2bd+2ac+2bd

                 = 4ac

Answer 2

ac-ad+bc-bd+c2+cd-bc-bd+2ac+2bd
= c2+3ac-ad+cd
=c(c+3a)-d(a-c)