0.5x+0.2y=0.09 1.3y-0.7z=0.05 -0.3x+2.1z=0.6解三元一次方程

0.5x+0.2y=0.09 ① 1.3y-0.7z=0.05 ②-0.3x+2.1z=0.6 ③②×3,得3.9y-2.1z=0.15 ④③+④,得3.9y-0.3x=0.75 ⑤①×3,⑤×5,得1.5x+0.6y=0.27 ⑥19.5y-1.5x=3.75 ⑦⑥+⑦,得20.1y=4.02y=0.2将y=0.2代入①中,得x=(0.09-...