列式與求解

1. 𝑦 - (𝑥-𝑦) = 5
𝑥 + (𝑥-𝑦) = 53
·········· (1)
·········· (2)
(1) ⇒ 𝑦 − 𝑥 + 𝑦 = 5
−𝑥 + 2𝑦 = 5
(2) ⇒ 𝑥 + 𝑥 − 𝑦 = 53
2𝑥 − 𝑦 = 53
·········· (3)
·········· (4)
設 師傅 的年齡為 𝑥，徒弟 的年齡為 𝑦

2. −𝑥 + 2𝑦 = 5
2𝑥 − 𝑦 = 53
·········· (3)
·········· (4)
(3) x 2
−2𝑥 + 4𝑦 = 10·········· (5)
(4) + (5)
3𝑦 = 63
𝑦 = 21

3. −𝑥 + 2𝑦 = 5
2𝑥 − 𝑦 = 53
·········· (3)
·········· (4)
𝑦 = 21 代入 (1)
−𝑥 + 42 = 5
−𝑥 = 5 − 42 = −37
𝑥 = 37

4. 𝑦 = 21
𝑥 = 37
因為假設 師傅 的年齡為 𝑥，徒弟 的年齡為 𝑦
所以知道
師傅的年齡為 37歲，徒弟的年齡為 21歲
A: 師傅的年齡為 37歲，徒弟的年齡為 21歲