Question

(a+b-c) * (a-b+c).please answer me fast please ​

Answer 1

(a+b-c) (a-b+c)

=a^2-(b-c) ^2. :using (a-b) (a+b)=a^2-b^2

=a^2-(b^2-2bc+c^2) :using (x-y) ^2=x^2-2xy+y^2

=a^2-b^2+2bc-c^2. :change all the sign when. there is a(-) sign in front of bracket.