Question

CM

a) (m+n)²-(m-n)²=4mn

b) (m+n)²+(m-n)²=2(m²+n²)

Answer 1

a. \(\left(m+n\right)^2-\left(m-n\right)^2=4mn\\ =\left(m+n-m+n\right)\left(m+n-+m-n\right)\\ =2n.2m\\ =4mn\left(ĐPCM\right)\)

 

Answer 2

a: \(VT=m^2+2mn+n^2-m^2+2mn-n^2=4mn=VP\)

b: \(VT=m^2+2mn+n^2+m^2-2mn+n^2\)

\(=2\left(m^2+n^2\right)=VP\)