(1)填:3.5
根据非负数之和为0得
2y-6=0
2x-3y+2=0
解得
y=3
2x-9+2=0得x=3.5
(2)填:6
3x²-4x+6=9
3x²-4x=3
2(3x²-4x)=6x²-8x=6