k1（1,1,3,1）+k2（3,-1,2,4）=（2,2,7,-1）=>k1+3k2 =2 (1)k1-k2=2 (2)3k1-k2 =7 (3)k1+4k2 =-1 (4)from (1) and (2)(1)-(2)k2 =0k1=2but k1=2 and k2=2 does not satisfy (3)=>α1,α2,α3 线性无关