Question
Solve the system: x + 2y = 13 3x − y = 5 What is the value of 2x + y?
Solution
ATQ, From x + 2y = 13 ⇒ x = 13 − 2y Substitute into 3x − y = 5: 3(13 − 2y) − y = 5 39 − 6y − y = 5 39 − 7y = 5 ⇒ 7y = 34 ⇒ y = 34/7 Then x = 13 − 2(34/7) = 13 − 68/7 = (91 − 68)/7 = 23/7 2x + y = 2(23/7) + 34/7 = (46 + 34)/7 = 80/7
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