Question

Prove that ab = 1/2[ (a+b)^2 - (a^2+b^2) ]

Answer 1

Expand the right side of the equation

Answer 2

yup

Answer 3

Exactly how? I try but I get stuck after I expand (a+b)^2

Answer 4

\((a+b)^2=a^2+2ab+b^2\)
The rest should be straightforward o.O...
just remember that if you have a negative infront of parentheses like this:
\(-(x+y)\) , the negative get's distributed: \(-(x+y)=-x-y\)