1. -7x²+11y²
2. mn²-(n-1)=n-(n-1)=1
3.因为2a²+3a+1=6,则2a²+3a=5整体代换
6a²+9a+5=3(2a²+3a)+5
=3*5+5
=20
4. =0
5.3a²-a-2=0则3a²-a=2
5+2a-6a²=5-2(3a²-a)=5-2*2
=1
1. -7x²+11y²
2. mn²-(n-1)=n-(n-1)=1
3.因为2a²+3a+1=6,则2a²+3a=5整体代换
6a²+9a+5=3(2a²+3a)+5
=3*5+5
=20
4. =0
5.3a²-a-2=0则3a²-a=2
5+2a-6a²=5-2(3a²-a)=5-2*2
=1