3x²-7x-6=x-12
3x²-8x+6=0
△=(-8)²-4×3×6=-8<0
方程无解在帮一道，嘿嘿。态度好即可采纳，本人一贯风格。y²+2my+2m²-1=0y²+2my+2m²-1=0 ， (y+m)²=1-m²△=4m²-4(2m²-1)=4-4m²=4(1-m²)当1-m²≥0即-1≤m≤1时，关于y的方程y²+2my+2m²-1=0有解，y=-m±√(1-m²)当1-m²<0即m<-1或m>1时，关于y的方程y²+2my+2m²-1=0无解