Question

x1,x2是方程x2+4x-6=0的两个实根

Answer 1

韦达定理

x1+x2=-4

x1x2=-6

x1^2+x2^2=(x1+x2)^2-2x1x2=16+12=28

x1^3+x2^3=(x1+x2)^3-3x1x2(x1+x2)

=(-4)^3-3(-6)(-4)=-64-72=-136

|x1-x2|^2=(x1+x2)^2-4x1x2=16+24=40

|x1-x2|=根号40