Question

已知x1 ,x2是方程x的平方+3x-5的两根,则x1-x2绝对值是?

Answer 1

(x1+1)(x2+1)=x1x2+x1+x2+1=-5-3+1=-7x1^2+x2^2=(x1+x2)^2-2x1x2=9-2*(-5)=19(x1-x2)^2=(x1+x2)^2-4x1x2=9-4*(-5)=29