a) x (x - y) + y (x - y) = x2 – xy+ yx – y2
= x2 – xy+ xy – y2
= x2 – y2
b) xn – 1 (x + y) – y(xn – 1 + yn – 1) =xn+ xn – 1y – yxn – 1 - yn
= xn + xn – 1y - xn – 1y - yn
= xn – yn.
a, x . (x - y) + y . (x - y)
= x2 - xy + xy - y2
= x2 - y2
b, xn - 1 . (x - y) - y. (xn - 1 + yn - 1)
= xn + xn - 1y - xn - 1y - yn
= xn - yn
CHÚC CÁC BẠN ĐẠT THÀNH TÍCH TỐT TRONG NĂM HỌC MỚI
a,x(x-y)+y(x-y)
=\(x^2\)-xy+xy-\(y^2\)
=\(x^2-y^2\)=(x-y)(x+y)
b,\(x^{n-1}\)\(\left(x+y\right)-y\left(x^{n-1}+y^{n-1}\right)\)
=\(x^n+x^{n-1}y-xy^{n-1}-y^n\)
=\(x^n+x^{n-1}y-x^{n-1}y^n\)
=\(x^n-y^n\)
a) \(x\left(x-y\right)+y\left(x-y\right)=\left(x-y\right)\left(x+y\right)=x^2-y^2\)
b) \(x^{n-1}\left(x+y\right)-y\left(x^{n-1}+y^{n-1}\right)\\ =x^n+y.x^{n-1}-y.x^{n-1}-y^n=x^n-y^n\)
a) x (x - y) + y (x - y) = x2 – xy+ yx – y2
= x2 – xy+ xy – y2
= x2 – y2
b) xn – 1 (x + y) – y(xn – 1 + yn – 1) =xn+ xn – 1y – yxn – 1 - yn
= xn + xn – 1y - xn – 1y - yn
= xn – yn.
