9x+4y=35 8x+3y=30

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9x+4y=358x+3y=309x+4y=358x+3y=309x+4y=358x+3y=309x+4y=35(1)8x+3y=30(2)(1)×3-(2)×4得:-5x=-15x=3代入(1)解得

9x+4y=35 8x+3y=30
9x+4y=35 8x+3y=30

9x+4y=35 8x+3y=30
9x+4y=35 (1)
8x+3y=30 (2)
(1)×3-(2)×4得:
-5x=-15
x=3
代入(1)解得:y=2
所以,方程组的解是:
x=3
y=2

相减 x+y=5,x=3,y=2

9x+4y=35 ①
8x+3y=30②
3①-4②得x=11
代入①得y=-16

9x+4y=35 (1)
8x+3y=30 (2)
(1)-(2)得x+y=5 (3)
(3)*3得 3x+3y=15 (4)
(2)-(4)得x=3 ,y=2

9X +4 Y = 35(1)
8X +3 Y = 30(2)
(!)×3,获得27X +12 Y = 105(3)

(2)×4有/> 32倍12为y = 120(4)
(4) - (3),是
5倍的= 15
= 3 BR /> X = 3到8倍+3 Y = 30,
24 +3 Y = 30
1612 = 6
Y = 2
所以x = 3时, = 2