\(a,=\left(x+y\right)^2-9=\left(x+y+3\right)\left(x+y-3\right)\\ b,=x\left(2x^2-2x+7x-7\right)=x\left(x-1\right)\left(2x+7\right)\)
a: =(x+y-3)(x+y+3)
b: \(=x\left(2x^2+5x-7\right)\)
\(=x\left(2x+7\right)\left(x-1\right)\)
\(a.\left(x+y-3\right)\left(x+y+3\right)\)
\(b.x\left(x-1\right)\left(2x+7\right)\)