b: =2y(x+3)+z(x+3)
=(x+3)(2y+z)
c: \(x^2+9x^3+x-9x\)
\(=x\left(x+1\right)+9x\left(x-1\right)\left(x+1\right)\)
\(=x\left(x+1\right)\left(1+9x-9\right)\)
\(=x\left(x+1\right)\left(9x-8\right)\)
h: =x(x+2)-y(x+2)
=(x+2)(x-y)
l: =2(x+y)-x(x+y)
=(x+y)(2-x)
`2xy + 3z + 6y + xz`
`= (2xy+xz)+(3z+6y)`
`=x(2y+z)+3(z+2y)`
`=(2y+z)(x+3)`