解方程组:(1)x+y=28 0.28x+0.4y=10 (2) 2x-1/5+3y-2/4=2 3x+1/3-3y+2/4=4/3

问题描述:

解方程组:(1)x+y=28 0.28x+0.4y=10 (2) 2x-1/5+3y-2/4=2 3x+1/3-3y+2/4=4/3

x+y=28 (1)0.28x+0.4y=10 (2)(1)*4得:4x+4y=112(3)(2)*10得:2.8x+4y=100(4)(3)-(4)并解得:x=10(5)将(5)代入(1)解得:y=182x-1/5+3y-2/4=2 (1)3x+1/3-3y+2/4=4/3(2)(1)*20得:40x-4+6...