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) (2)
(3) (4)
(5) (6)
(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
···································· 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
|
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
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