用加减消元法家下列方程组:(1){3x-4y=1,5x+2y=6(2){3x+5y=25,4x+3y=15(3){2x-3y=8,7x-5y=-5(4){2分之x+3分之y=16,3分之x-4分之y=5(5){3x+2y=2,x-2y=6(6){2p+5q=-9,4p-5q=-3(7){3x-2y=-1,3x-4y=-5(4){6x+5z=5,3x+4z=-5
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![用加减消元法家下列方程组:(1){3x-4y=1,5x+2y=6(2){3x+5y=25,4x+3y=15(3){2x-3y=8,7x-5y=-5(4){2分之x+3分之y=16,3分之x-4分之y=5(5){3x+2y=2,x-2y=6(6){2p+5q=-9,4p-5q=-3(7){3x-2y=-1,3x-4y=-5(4){6x+5z=5,3x+4z=-5](/uploads/image/z/224824-40-4.jpg?t=%E7%94%A8%E5%8A%A0%E5%87%8F%E6%B6%88%E5%85%83%E6%B3%95%E5%AE%B6%E4%B8%8B%E5%88%97%E6%96%B9%E7%A8%8B%E7%BB%84%EF%BC%9A%EF%BC%881%EF%BC%89%7B3x-4y%3D1%2C5x%2B2y%3D6%EF%BC%882%EF%BC%89%7B3x%2B5y%3D25%2C4x%2B3y%3D15%EF%BC%883%EF%BC%89%7B2x-3y%3D8%2C7x-5y%3D-5%EF%BC%884%EF%BC%89%7B2%E5%88%86%E4%B9%8Bx%2B3%E5%88%86%E4%B9%8By%3D16%2C3%E5%88%86%E4%B9%8Bx-4%E5%88%86%E4%B9%8By%3D5%EF%BC%885%EF%BC%89%7B3x%2B2y%3D2%2Cx-2y%3D6%EF%BC%886%EF%BC%89%7B2p%2B5q%3D-9%2C4p-5q%3D-3%287%29%7B3x-2y%3D-1%2C3x-4y%3D-5%284%29%7B6x%2B5z%3D5%2C3x%2B4z%3D-5)
用加减消元法家下列方程组:(1){3x-4y=1,5x+2y=6(2){3x+5y=25,4x+3y=15(3){2x-3y=8,7x-5y=-5(4){2分之x+3分之y=16,3分之x-4分之y=5(5){3x+2y=2,x-2y=6(6){2p+5q=-9,4p-5q=-3(7){3x-2y=-1,3x-4y=-5(4){6x+5z=5,3x+4z=-5
用加减消元法家下列方程组:(1){3x-4y=1,5x+2y=6(2){3x+5y=25,4x+3y=15
(3){2x-3y=8,7x-5y=-5(4){2分之x+3分之y=16,3分之x-4分之y=5(5){3x+2y=2,x-2y=6(6){2p+5q=-9,4p-5q=-3(7){3x-2y=-1,3x-4y=-5(4){6x+5z=5,3x+4z=-5
用加减消元法家下列方程组:(1){3x-4y=1,5x+2y=6(2){3x+5y=25,4x+3y=15(3){2x-3y=8,7x-5y=-5(4){2分之x+3分之y=16,3分之x-4分之y=5(5){3x+2y=2,x-2y=6(6){2p+5q=-9,4p-5q=-3(7){3x-2y=-1,3x-4y=-5(4){6x+5z=5,3x+4z=-5
(1){3x-4y=1①,5x+2y=6②
②×2 10x+4y=12 ③
③+① 13x=13 x=1
②×3 15x+6y=18④
①×5 15x-20y=5⑤
④-⑤ 26y=13 y=1/2
x=1,y=1/2
(2){3x+5y=25①,4x+3y=15②
①×4 12x+20y=100③
②×3 12x+9y=45④
③-④ 11y=55 y=5
①×3 9x+15y=75⑤
②×5 20x+15y=75⑥
⑤-⑥ 11x=0 x=0
x=0,y=5
(3){2x-3y=8①,7x-5y=-5②
①×7 14x-21y=56③
②×2 14x-10y=-10④
④-③11y=-66 y=-6
①×5 10x-15y=40⑤
②×3 21x-15y=-15⑥
⑥-⑤ 11x=-55 x=-5
x=-5,y=-6
(4){2分之x+3分之y=16,3分之x-4分之y=5
整理得:3x+2y=96①,4x-3y=60②
①×4 12x+8y=384③
②×3 12x-9y=180④
③-④ 17y=204 y=12
①×3 9x+6y=288⑤
②×2 8x-6y=120⑥
⑤+⑥ 17x=408 x=24
x=24,y=12
(5){3x+2y=2①,x-2y=6②
①+②4x=8 x=2
②×3 3x-6y=18③
①-③ 8y=-16 y=-2
x=2,y=-2
(6){2p+5q=-9①,4p-5q=-3②
①×2 4p+10q=-18③
③-② 15q=-15 q=-1
①+② 6p=-12 p=-2
p=-2,q=-1
(7){3x-2y=-1①,3x-4y=-5②
①-② 2y=4 y=2
①×2 6x-4y=-2③
③-② 3x=3 x=1
x=1,y=2
(4){6x+5z=5①,3x+4z=-5②
②×2 6x+8z=-10③
③-① 3z=-15 z=-5
①×4 24x+20z=20④
②×5 15x+20z=-25⑤
④-⑤ 9x=45 x=5
x=5,z=-5