Question

六x-2x^2-3x+x^2+1,合并同类项

先合并同类项再计算 求代数式的值
求代数式的值
6x+2x^2-3x+x^2+1 其中x= -5
4x^2+3xy-x^2-9 其中x=2 y= -3
1/3m-3/2n-5/6n-1/6m 其中m=6 n=2
3pq-4/5m-4pq 其中m=5 p=1/3 q=-3/2
要求具体

Answer 1

6x+2x^2-3x+x^2+1
=2x^2 +x^2+6x-3x+1
=3x^2+3x+1
=3×（-5）^2+3×（-5）+1=61
4x^2+3xy-x^2-9
=4x^2-x^2+3xy-9
=3x^2+3xy-9
=3×2^2+3×2×（-3）-9=-15
1/3m-3/2n-5/6n-1/6m
=1/3m-1/6m -3/2n-5/6n
=1/6m -7/3n
=1/6×6-7/3×2
=-11/3
3pq-4/5m-4pq
=3pq-4pq-4/5m
=-pq-4/5m
=-1/3×（-3/2)-4/5×5
=-7/2=-3又2分之1