Question

H·y viÕt c¸c biÓu thøc d­íi d¹ng tæng cña ba b×nh ph­ong;

(a + b + c)² + a² + b² + c² 

mình ko biết tổng ba bình phong là gì

Answer 1

\(=\left(a+b\right)^2+\left(b+c\right)^2+\left(c+a\right)^2\)

Answer 2

(a + b + c)² + a² + b² + c²

=a²+b²+c²+2ab+2ac+2bc+a²+b²+c²

=(a²+2ab+b²)+(b²+2bc+c²)+(a²+2ac+c²)

=(a+b)²+(b+c)²+(a+c)²

Answer 3

\(\left(a+b+c\right)^2+a^2+b^2+c^2\)

\(=\left(a^2+2ab+b^2\right)+\left(b^2+2bc+c^2\right)+\left(a^2+2ac+c^2\right)\)

\(=\left(a+b\right)^2+\left(b+c\right)^2+\left(a+c\right)^2\)