方法一:
2X-3Y=11-4M①
3X+2Y=21+5M②
①×2+②×3:13X=2(11-4M)+3(21+5M)
13X=85+7M
X=(85+7M)/13
代入②:3(85+7M)/13+2Y=21+5M
2Y=[13(21+5M)-3(85+7M)]/13
Y=(9+22M)/13
解得:X=(85+7M)/13
Y=(9+22M)/13
把X,Y的值代入X+3Y=10+7M
得:(85+7M)/13+3(9+22M)/13=10+7M
85+7M+27+66M=13(10+7M)
112+73M=130+91M
18M=-18
M=-1
方法二:
X+3Y=(-7/13)(2X-3Y)+(9/13)(3X+2Y)
10+7M=(-7/13)(11-4M)+(9/13)(21+5M)
13(10+7M)=-7(11-4M)+9(21+5M)
130+91M=-77+28M+189+45M
130+91M=112+73M
18M=-18
M=-1
求助一道二元一次方程题
求助一道二元一次方程题
已知满足2X-3Y=11-4M和3X+2Y=21+5M的X,Y也满足X+3Y=10+7M,求M的值
已知满足2X-3Y=11-4M和3X+2Y=21+5M的X,Y也满足X+3Y=10+7M,求M的值
数学人气:506 ℃时间:2020-04-22 20:56:19
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