Question

CMR các BT sau luôn bg 0

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

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

GIÚP MK VS MK ĐG CẦN GẤP

Answer 1

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

= xy - xz + zy - xy + xz - yz

= ( xy - xy ) - ( xz - xz ) + ( zy - yz )

= 0 - 0 + 0

= 0 ( đpcm )

Answer 2

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

= xy + xz - xyz - yz - xy + xyz + zy - zx

= ( xy - xy ) + ( xz - zx ) - ( xyz - xyz ) - ( yz - zy )

= 0 + 0 - 0 - 0

= 0 ( đpcm )

Answer 3

Ko cần tính theo kiểu của Bonking, tính ntn cx đc

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

= xy - xz + y(z - x) + z(x - y)

= xy - xz + yz - xy + z(x - y)

= xy - xz + yz - xy + xz - yz

= 0

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

= xy + xz - xyz - yz - y(z + x - xz) + z(y - z)

= xy + xz - xyz - yz - xy - xy + xyz + z(y - x)

 = xy + xz - xyz - yz - xy - xy + xyz + xyz + yz - xz

= 0