Question

当K为何值时,方程组x平方+y平方=16和x-y=k有解

Answer 1

x-y=k

x=y+k

(y+k)^2+y^2=16

2y^2+2yk+k^2-16=0

△=4k^2-8(k^2-16)≥0

-4k^2+8*16≥0

k^2≤32

-4√2≤k≤4√2