k1+k2+k3+k4+k5+k6+k7+k8=20 3k1+3.5k2+4k3+4.5k4+5k5+5.5k6+6k7+6.5k8=89.5
问题描述：
k1+k2+k3+k4+k5+k6+k7+k8=20 3k1+3.5k2+4k3+4.5k4+5k5+5.5k6+6k7+6.5k8=89.5
答
这有8个未知数，可只有2个方程，这是所有条件了吗？
答
方程的秩为2,解为k1(1,-2,1,0,0,0,0,0,)t+k2(2,-3,0,1,0,0,0,0)t+k3(3,-4,0,0,1,0,0,0)t……+k6（6,-7,0,0,0,0,0,0,1）t+(-139,20,0,0,0,0,0,0)t,其中k1,k2……k6为任意值,不知道是不是这么解得