根据韦达定理知道,x1+x2等于1,x1乘以x2得负3.x1²+x2²=﹙x1+x2﹚²-2x1·x2=1的平方-2乘以负3=1+6=7
x1+x2=1 x1x2=-3 x1平方+x2平方=(x1+x2)^2-2x1x2=1+6=7
x1²+x2²=﹙x1+x2﹚²-2x1·x2=1+6=7