b: \(=y\left(x^2-9\right)-x\left(x^2-9\right)\)
\(=\left(y-x\right)\left(x-3\right)\left(x+3\right)\)
i: \(=5\left(x^2-2x-xy+2y\right)\)
\(=5\left[x\left(x-2\right)-y\left(x-2\right)\right]\)
\(=5\left(x-2\right)\left(x-y\right)\)
b, \(x^2y-9y+9x-x^3\)
\(=\left(x^2y-x^3\right)-\left(9y-9x\right)\)
\(=x^2\left(y-x\right)-9\left(y-x\right)\)
\(=\left(x^2-9\right)\left(y-x\right)\)
\(=\left(x-3\right)\left(x+3\right)\left(y-x\right)\)
i, \(5x^2-10x-5xy+10y\)
\(=\left(5x^2-5xy\right)-\left(10x-10y\right)\)
\(=5x\left(x-y\right)-10\left(x-y\right)\)
\(=\left(x-y\right)\left(5x-10\right)\)
`b, x^2(y-x) - 9(y-x)`
`= (x^2-9)(y-x)`
`= (x-3)(x+3)(y-x)`
`i, 5x(x-2) - 5y(x-2)`
`= 5(x-y)(x-2)`
