解方程组；2x+3y=12,3x+4y=17
\u89e3\u4e0b\u5217\u65b9\u7a0b\u7ec4 2x+3y=12 3x+4y=172x+3y=12\u2460 3x+4y=17\u2461 \uff0c\u2460\u00d73\u5f97\uff0c6x+9y=36\u2462\uff0c\u2461\u00d72\u5f97\uff0c6x+8y=34\u2463\uff0c\u2462-\u2463\u5f97\uff0cy=2\uff0c\u628ay=2\u4ee3\u5165\u2460\u5f97\uff0c2x+3\u00d72=12\uff0c\u89e3\u5f97x=3\uff0c\u6240\u4ee5\uff0c\u65b9\u7a0b\u7ec4\u7684\u89e3\u662f x=3 y=2 \uff0e
2x+3y=12 (1)
3x-4y=17 (2)
\u7531(1)\u5f97y=(12-2x)/3
\u4ee3\u5165(2)
4x-(48-8x)/3=17
12x-48+8x=51
20x=99
\u6240\u4ee5
x=99/20
y=(12-2x)/3=7/10
3x+4y=17 ②
解： ①×3，②×2 得
6x+9y=36 ③
6x+8y=34 ④
③-④得
6x+9y-6x-8y=2
y=2
将y=2代入②，得
3x+4×2=17
x=3
∴x=3，y=2
绛旓細2x+3y=12 (1)3x-4y=17 (2)鐢(1)寰梱=(12-2x)/3 浠ｅ叆(2)4x-(48-8x)/3=17 12x-48+8x=51 20x=99 鎵浠 x=99/20 y=(12-2x)/3=7/10
绛旓細2x+3y=12 鈶 3x+4y=17 鈶 瑙ｏ細 鈶犆3锛鈶∶2 寰 6x+9y=36 鈶 6x+8y=34 鈶 鈶-鈶ｅ緱 6x+9y-6x-8y=2 y=2 灏唝=2浠ｅ叆鈶★紝寰 3x+4脳2=17 x=3 鈭磝=3锛寉=2
绛旓細灏唜椤圭殑绯绘暟鍖栦负鐩哥瓑锛屽皢y椤圭殑绯绘暟鍖栦负浜掍负鐩稿弽鏁帮紝杩欐槸瑙ｆ柟绋鐨勬瘮杈冪畝鍗曠殑鏂规硶銆傛棰樺彲瑙ｄ负锛2x+3y=12锛1锛3x-4y=17锛2锛(1)*3 寰楋細6x+9y=36 (3)(2)*2 寰楋細6x-8y=34 (4)(3)-(4)寰楋細17y=2 瑙ｅ緱y=2/17 鎶妝=2/17浠ｅ叆锛1锛 瑙ｅ緱x=99/17 鏂规硶2鍚岀悊锛岃嚜宸瑙ｈВ璇...
绛旓細2x+3y=12 (1)3x-4y=17 (2)鐢(1)寰梱=(12-2x)/3 浠ｅ叆(2)4x-(48-8x)/3=17 12x-48+8x=51 20x=99 鎵浠 x=99/20 y=(12-2x)/3=7/10
绛旓細2x+3y=12 (1)3x+4y=17 (2)(2)*3-(2)*2 9y-8y=36-34 y=2 (2)*3-(1)*4 9x-8x=51-48 x=3 3锛坸-1锛=y+5 (3)5锛坹-1锛=3锛坸+5锛 (4)(3)鏁寸悊 3x-3=y+5 3x-y=8 (5)(4)鏁寸悊 5y-5=3x+15 3x-5y=-20 (6)(5)-(6)-y+5y=8+20 4y=...
绛旓細鍥犱负x:y=3:2,鎵浠2x=3y,鍥犱负2x+3y=12锛灏辨槸3y+3y=12,鎵浠=2,x=3y/2=3*2/2=3
绛旓細瑙ｏ細锛1锛墈2x+3y=12鈶3x+4y=17鈶★紝鈶犆3-鈶∶2寰9y-8y=36-34锛岃В寰梱=2锛屾妸y=2浠ｅ叆鈶犲緱2x+3脳2=12锛瑙ｅ緱x=3锛屾墍浠鏂圭▼缁鐨勮В涓簕x=3y=2锛涳紙2锛夊師寮=3鈭2+鈭8脳鈭2-鈭2鈭2脳鈭2-鈭2 =3鈭2+4-鈭22-鈭2 =3鈭22+2锛
绛旓細2x+3y=12 3x=+1 x=1/3,2/3+3y=12,3y=34/3,y=34/3,鈭磠 x=1/3, y=34/9.
绛旓細2x涓3y锛12锛鈶 3x鍗乤y锛5鈶 灏唜锛漜锛寉锛濅竴2鍒嗗埆浠ｅ叆鈶犮佲憽寰 2c涓3脳锛堜竴2锛夛紳12锛屸憿 3c鍗乤脳锛堜竴2锛夛紳5鈶 鍖栫畝鈶付鈶ｅ緱 2c鍗6锛12锛3c涓2a锛5銆傝В涔嬪緱c锛3锛宎锛2 4a锛媍锛4脳2鍗3锛11
绛旓細瀛︿範鎰夊揩锛
