题目内容
解下列方程组.(每小题5分,共30分)
(1)
(2) 
(3)
(4) 
(5)
(6) 
(1)


(3)


(5)


(1)
(2)
(3)
(4)
(5)
(6)






(1) 解:将②代入①得


···································· 2分
将
代入②得
························· 4分
∴
是原方程组的解··························· 5分
(2) 解:①+②得
···································· 2分
将
代入①得

···································· 4分
∴
是原方程组的解··························· 5分
(3) 解:②-①得

···································· 2分
将
代入①得


∴
是原方程组的解··························· 5分
(4) 解:原方程组变形为
···················· 1分由①得
③
由②得
④
③+④得
x =" 8···························" 3分
将x = 8代入④得 y =" 1····························" 4分
∴
是原方程组的解···························· 5分
(5) 解:由①得
③································ 1分
由②得
④································ 2分
③×2得
⑤
④×3得
⑥
⑤-⑥得
····································· 3分
将y = 1代入④得
····································· 4分
∴
是原方程组的解···························· 5分
(6) 解:①+②得
③·································· 1分
①-②得
④·································· 2分
③+④得
····································· 3分
将
代入③得y =" –" 2 ··························· 4分
∴
是原方程组的解 5分




将


∴

(2) 解:①+②得


将




∴

(3) 解:②-①得



将




∴

|


由②得

③+④得

将x = 8代入④得 y =" 1····························" 4分
∴

(5) 解:由①得


由②得


③×2得

④×3得

⑤-⑥得


将y = 1代入④得


∴

(6) 解:①+②得


①-②得


③+④得


将

∴


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