七年级下册数学补充习题55.56业答案,要过程啊.
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七年级下册数学补充习题55.56业答案,要过程啊.
![七年级下册数学补充习题55.56业答案,要过程啊.](/uploads/image/z/2256353-17-3.jpg?t=%E4%B8%83%E5%B9%B4%E7%BA%A7%E4%B8%8B%E5%86%8C%E6%95%B0%E5%AD%A6%E8%A1%A5%E5%85%85%E4%B9%A0%E9%A2%9855.56%E4%B8%9A%E7%AD%94%E6%A1%88%2C%E8%A6%81%E8%BF%87%E7%A8%8B%E5%95%8A.)
题目呢
再问: (1)y=x+2,2x-y=-1,。(2)x-y=1,2x+3y=-8.(3)s+2t=7,5s-3t=9. (4)3x-4y+1=0,2x+y+8=0
再答: y=x+2 (1) y=2x+1 (2) (2)-(1)得 x=-1 x带入(1)得y=1 x-y=1 (1) 2x+3y =-8 (2) (1)乘3+(2)得5x=-5 x=-1 x带入(1)得y=-2 s+2t=7 (1) 5s-3t=9 (2) (1)乘3+(2)乘2得 13s=39 s=3 s带入(1)得t=2 3x-4y+1=0(1) 2x+y+8=0(2) (1)+(2)乘4得11x=33 x=3 x带入(1)得y=2
再问: (1)y=x+2,2x-y=-1,。(2)x-y=1,2x+3y=-8.(3)s+2t=7,5s-3t=9. (4)3x-4y+1=0,2x+y+8=0
再答: y=x+2 (1) y=2x+1 (2) (2)-(1)得 x=-1 x带入(1)得y=1 x-y=1 (1) 2x+3y =-8 (2) (1)乘3+(2)得5x=-5 x=-1 x带入(1)得y=-2 s+2t=7 (1) 5s-3t=9 (2) (1)乘3+(2)乘2得 13s=39 s=3 s带入(1)得t=2 3x-4y+1=0(1) 2x+y+8=0(2) (1)+(2)乘4得11x=33 x=3 x带入(1)得y=2