Question

Answer 1

1) \(x\left(x+3\right)+\left(x-2\right)\left(3-x\right)\)

\(=x^2+3x-x^2+5x-6=8x-6\)

2) \(\left(x-7\right)^2-\left(x+4\right)\left(x-3\right)=-2\)

\(\Leftrightarrow x^2-14x+49-x^2-x+12=-2\)

\(\Leftrightarrow-15x=-63\Leftrightarrow x=\dfrac{21}{5}\)

3) \(3x^2-3xy-5x+5y=3x\left(x-y\right)-5\left(x-y\right)=\left(x-y\right)\left(3x-5\right)\)

Answer 2

\(1,=x^2+3x-x^2+5x-6=8x-6\\ 2,\Leftrightarrow x^2-14x+49-x^2-x+12=-2\\ \Leftrightarrow-15x=-63\\ \Leftrightarrow x=\dfrac{21}{5}\\ 3,=3x\left(x-y\right)-5\left(x-y\right)=\left(3x-5\right)\left(x-y\right)\)