Question

化简求值:当x=4,y=5,z=2时,求x的平方+2yz-y的平方-z的平方/x的平方-2xy-z的

Answer 1

x的平方+2yz-y的平方-z的平方/x的平方-2xy-z的平方+y的平方

=[x²-（y-z）²]/[(x-y)²-z²]

=(x+y-z)(x-y+z)/(x-y+z)(x-y-z)

=(x+y-z)/(x-y-z)

=(4+5-2)/(4-5-2)

=7/(-3)

=-7/3