答:
1)
(x^2+1)-3x(x-1)+2(x^2+x-1),其中x=102/5
=x^2+1-3x^2+3x+2x^2+2x-2
=5x-1
=102-1
=101
2)
5(x^2+x-3)-4x(6+x)+x(4-x)=0
5x^2+5x-15-24x-4x^2+4x-x^2=0
-15x-15=0
-15x=15
x=-1
答:
1)
(x^2+1)-3x(x-1)+2(x^2+x-1),其中x=102/5
=x^2+1-3x^2+3x+2x^2+2x-2
=5x-1
=102-1
=101
2)
5(x^2+x-3)-4x(6+x)+x(4-x)=0
5x^2+5x-15-24x-4x^2+4x-x^2=0
-15x-15=0
-15x=15
x=-1