Question

已知x-y=2，y-z=2，x+z=14，求x²-z²的值。

过程~~~~~~~

Answer 1

∵x-y=2，y-z=2
∴x-y+y-z = x-z =2+2 = 4
∴x²-z²=(x-z)(x+z)=4×14=56

Answer 2

x-y=2，y-z=2

x-y+y-z=2+2

x-z=4

x+z=14

x²-z²

=(x-z)(x+z)
=4*14
=56