a) \(7\left(3x-2\right)+y\left(3x-2\right)=\left(3x-2\right)\left(7+y\right)\)
b) \(x\left(y-x\right)-3\left(x-y\right)=x\left(y-x\right)+3\left(y-x\right)=\left(y-x\right)\left(x+3\right)\)
c) \(x^2-6xy+9y^2=\left(x-3y\right)^2\)
a. 7(3x - 2) + y(3x - 2)
= (7 + y)(3x - 2)
b. x(y - x) - 3(x - y)
= x(y - x) + 3(y - x)
= (x + 3)(y - x)
c. x2 - 6xy + 9y2
= x2 - 3y.x.2 + (3y)2
= (x - 3y)2