Question

已知两个有理数xy满足等式x3+2y+√5*y=17-5√5求√2(x-y)的值

Answer 1

x³+2y+√5*y=17-5√5

xy是有理数

则,

x³+2y=17

√5*y=-5√5

解得,x=3 ,y= -5

√2(x-y)

=√2(3+5)

=8√2

如果x,y也在根号下,则

√[2(x-y)]

=√2(3+5)

=4