x1-x2+3x3+2x4=3 2x1-x2+2x3-x4=2 x1-2x2+7x3+7x4=t 求参数t使方程组有...答:x1-x2+3x3+2x4=3 ① 2x1-x2+2x3-x4=2 ② x1-2x2+7x3+7x4=t③ ①-③,x2-4x3-5x4=3-t,②-①*2,x2-4x3-5x4=-4,④ 方程组有解,∴3-t=-4,t=7,这时方程组的解是x3=m,x4=n,由④,x2=4m+5n-4,代入①,x1=x2-3x3-2x4+3=m+3n-1,∴{x1=m+3n-1,{x2=4...
x1-x2+3x3+2x4=3 2x1-x2+2x3-x4=2 x1-2x2+7x3+7x4=t 求参数t使方程组有...答:x1-x2+3x3+2x4=3 ①2x1-x2+2x3-x4=2 ②x1-2x2+7x3+7x4=t③①-③,x2-4x3-5x4=3-t,②-①*2,x2-4x3-5x4=-4,④方程组有解,∴3-t=-4,t=7,这时方程组的解是x3=m,x4=n,由④,x2=4m+5n-4,代入①,x1=x2-3x3-2x4+3=m+3n-1,∴{x1...