Question

4x²y-［6xy-2（4xy-2）-x²y］+1

已知X=二分之一，Y=1 先化简再求值

Answer 1

4x²y-［6xy-2（4xy-2）-x²y］+1
=4x²y-（6xy-8xy+4-x²y）+1
=4x²y+2xy-4+x²y+1
=5x²y+2xy-3
因为x=1/2，y=1
所以
原式子=5/4+1-3=-3/4
祝开心

追问

求值的那个详细点

追答

=5x²y+2xy-3
=5×（1/2)²×1+2×1/2×1-3
=5/4+1-3
=5/4-2
=-3/4
祝开心

追问

X=﹣二分之一

追答

=5x²y+2xy-3
=5×（-1/2)²×1+2×(-1/2)×1-3
=5/4-1-3
=5/4-4
=-11/4
祝开心

追问

应该是四分之五+负一-3吧

追答

四分之五+负一-3
=4分之5减4
=负4分之11

Answer 2

4x^2y-[6xy-2(4xy-2)-x^2y]+1
=4x^2y-(4-2xy-x^2y)+1
=5x^2y+2xy-3
=xy(5x+2)-3
=1/2*(5*1/2+2)-3
=7/4-3
=-5/4