Question
If 4x2 + y2 = 40 and xy = 6, then
find the value of 2x + y.Solution
ATQ, (2x+y)2 = (2x)2 + y2 + (2 × 2x × y) = (2x+y)2 = (4x2 + y2) + 4xy = (2x + y)2 = 40 + 4 × 6 ⇒ (2x + y)2 = 64 = 2x + y = ±64 = 2x + y = ±8
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