Question

Bài 1: Rút gọn:
a,(x+y)\(^2\)+(x-y)\(^2\)
b, 2(x-y)(x+y)+(x+y)\(^2\)+(x-y)\(^2\)
c,(x-y+z)\(^2\)+(z-y)\(^2\)+2(x-y+z)(y-z)

Answer 1

\(a.\left(x+y\right)^2+\left(x-y\right)^2=x^2+2xy+y^2+x^2-2xy+y^2\)

\(=2x^2+2y^2=2\left(x^2+y^2\right)\)

\(b.2\left(x-y\right)\left(x+y\right)+\left(x+y\right)^2+\left(x-y\right)^2\)

\(=\left(x+y+x-y\right)^2=4x^2\)

\(c.\left(x-y+z\right)^2+\left(z-y\right)^2+2\left(x-y+z\right)\left(y-z\right)\)

\(=\left(x-y+z+y-z\right)^2=x^2\)

Answer 2

a ) \(\left(x+y\right)^2+\left(x-y\right)^2\)

\(=x^2+2xy+y^2+x^2-2xy+y^2\)

\(=2x^2+2y^2=2\left(x^2+y^2\right)\)

b ) \(2\left(x-y\right)\left(x+y\right)+\left(x+y\right)^2+\left(x-y\right)^2\)

\(=\left(x+y+x-y\right)^2\)

\(=\left(2x\right)^2=4x^2\)

c ) \(\left(x-y+z\right)^2+\left(z-y\right)^2+2\left(x-y+z\right)\left(y-z\right)\)

\(=\left(x-y+z\right)^2+\left(y-z\right)^2+2\left(x-y+z\right)\left(y-z\right)\)

\(=\left(x-y+z+y-z\right)^2\)

\(=x^2\)

Answer 3

nek mày đăng bài ở lớp lên đây hỏi ak