a) `9xyz + 18xy^2 z^2 - 27y^2 z = 9yz ( x + 2yz - 3y)`
b) `4x(x-2y) +8y(2y-x) = 4x(x-2y) - 8y(x-2y)`
`= (x-2y)(4x-8y) = 4(x-2y)(x-2y) = 4(x-2y)^2`
c) `4x^2 (x-y) - 10y (y-x) = 4x^2 (x-y)+ 10y (x-y) = (x-y)(4x^2+10y)`
d) `x(x-1) + (1-x)^2 = x(x-1) + (x-1)^2 = (x-1)(x+x-1) = (x-1)(2x-1)`
e) `10x - x^2 - 25 = -(x^2 - 2.x.5 + 5^2) = -(x-5)^2`
g) `25-(3-x)^2 = 5^2 - (3-x)^2 = (5+3-x)(5-3+x) = (8-x)(2+x)`