Question

求下列各式的值:x(x+2y)-(x+1)^2+2X,其中x=1/25,y=-25

Answer 1

x(x+2y)-(x+1)^2+2x

=x^2+2xy-x^2-2x-1+2x

=2xy-1

=2*(1/25)*(-25)-1

=-2-1

=-3