Question

Chứng minh: 2(a+b+c)(\(\dfrac{b}{2}\)+\(\dfrac{c}{2}\)-\(\dfrac{a}{2}\))=2bc+c\(^2\)+b\(^2\)-a\(^2\)

Answer 1

VT = (a+b+c)(b+c-a)

VP = (c+b)²-a²=(c+b-a)(c+b+a)

Vậy VT = VP