Question

3x(-5+x)

(8-2x)(x+5)

Answer 1

\(3x\left(-5+x\right)=3x^2-15x\\ \left(8-2x\right)\left(x+5\right)=8x+40-2x^2-10x=-2x^2-2x+40\)

Answer 2

\(3x\left(-5+x\right)\Leftrightarrow-15x+3x^2\)

\(\left(8-2x\right)\left(x+5\right)\Leftrightarrow8x+40-2x^2-10x\Leftrightarrow40-2x^2-2x\)