若x+y-2=0,3a²-a-2=0,求多项式5-3a²x+ax-3a²y+ay的值.
问题描述：
若x+y-2=0,3a²-a-2=0,求多项式5-3a²x+ax-3a²y+ay的值.
答
x+y-2=0,x+y=2
3a²-a-2=0,3a²-a=2
5-3a²x+ax-3a²y+ay
=5-3a²x-3a²y+ax+ay
=5-3a²(x+y)+(x+y)a
=5-6a²+2a
=5-2(3a²-a)
=5-4
=1
答
x+y=2,3a²-a=2
5-3a²x+ax-3a²y+ay
=5-x(3a²-a)-y(3a²-a)
=5-(x+y)(3a²-a)
=5-2*2=1
答
x+y-2=0
∴x+y=2
3a²-a-2=0
∴3a²-a=2
5-3a²x+ax-3a²y+ay
=5-3a²(x+y)+a(x+y)
=5-6a²+2a
=5-2(3a²-a)
=5-2×2
=1
答
5-3a²x+ax-3a²y+ay
=-3a²(x+y)+a(x+y)+2(x+y) +5-2(x+y)
=-(x+y)(3a²-a-2)+1-2(x+y-2)
=1