Question

Chứng minh: 
a(a - 1) + 2(3 - a) + 3a = a² + 6

Answer 1

\(a\left(a-1\right)+2\left(3-a\right)+3a=a^2-a+6-2a+3a\)

\(=a^2+6-3a+3a\)

\(=a^2+6\)

Answer 2

\(a^2-a+6-2a+3a-a^2-6=0\Leftrightarrow6-6=0\)