Question

1 . Tính giá trị biểu thức

a) ( x + y + z )( x+ y + z)

b) ( x- y + z )(x- y - z )

c) ( x - 1 + y )(x - 1 - y )

Mình cần kíp lắm giúp với.

Answer 1

\(a.\left(x+y+z\right)\left(x+y+z\right)=x^2+xy+xz+xy+y^2+zy+zx+zy+z^2=x^2+y^2+z^2+2xy+2zy+2zx\)

\(b.\left(x-y+z\right)\left(x-y-z\right)=x^2-xy-zx-xy+y^2+zy+zx-zy-z^2=x^2+y^2-z^2-2xy\)

\(c.\left(x-1+y\right)\left(x-1-y\right)=x^2-x-xy-x+1+y+xy-y-y^2=x^2-y^2-2x+1\)

Answer 2

a) = \(^{\left(x+y+z\right)^2}\)=\(x^2\)+\(y^2\)+\(z^2\)+ 2xy +2xz+2yz

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

c)= \(\left(x-1\right)^2\)-\(y^2\)= \(x^2\)-2x+1 - \(y^2\)