\(a,=\left(x-y\right)\left(x+y\right)+11\left(x-y\right)=\left(x-y\right)\left(x+y+11\right)\\ b,=\left(x+z\right)\left(x^2-xz+z^2\right)+y\left(x^2+z^2-xz\right)\\ =\left(x^2-xz+z^2\right)\left(x+y+z\right)\)
a. x2 - y2 + 11x - 11y
= (x + y)(x - y) + 11(x - y)
= (x + y + 11)(x - y)
b. Mik ko hiểu đề lắm