Giải toán 8 tập 1: Câu 47 sgk trang 22

a) \(x^2 - xy + x - y\)
\(= (x^2 - xy) + (x - y)\)
\(= x(x - y) + (x - y)\)
\(= (x - y)(x + 1)\)
b) \(xz + yz - 5(x + y)\)
\(= z(x + y) - 5(x + y)\)
\(= (x + y)(z - 5)\)
c) \(3x^2 - 3xy - 5x + 5y\)
\(= (3x^2 - 3xy) - (5x - 5y)\)
\(= 3x(x - y) - 5(x - y)\)
\(= (x - y)(3x - 5)\)