已知（m²+n²+2）²=9 则2m²+2n²为?

已知（m²+n²+2）²=9 则2m²+2n²为?
已知（m²+n²+2）²=9 则2m²+2n²为?

已知（m²+n²+2）²=9 则2m²+2n²为?
∵(m²+n²+2)²=9,且m²+n²≥0
∴m²+n²+2=3即m²+n²=1
∴2m²+2n²=2

（m²+n²+2）²=9
m²+n²+2=±3
m²+n²=-5 或1
2m²+2n²=2（m²+n²）=-10或2