Question

1.已知x²+y²+4x-6y+13=0,则x的y次方等于几?

Answer 1

1.x²+y²+4x-6y+13=（x+2）²+（y-3）²=0

所以x=-2,y=3

x的y次方=-2³=-8

2.（a³-ab²）/（a²b-ab²）÷[1+（a²+b²／2ab）]+[2（a²b-ab²+b³）]／（a³+b³）

=[（a²-b²﹚/(ab-b²)]/[(a+b)²/2ab]+2（a²b-ab²+b³)/[a+b)(a²-ab+b²)]

=2a/(a+b)+2b/(a+b)

=2

3.由韦达定律得

x1+x2=4-k²=0

x1x2=k+1=-1

所以k=-2