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TS EAMCET · Maths · Sequences and Series

If \(x\) and \(y\) are two positive integers such that \(x+2 y=10\) and \(x^2 y^3\) is maximum then \(x^2+2 y^3=\)

  1. A 34
  2. B 137
  3. C 43
  4. D 70
Verified Solution

Answer & Solution

Correct Answer

(D) 70

Step-by-step Solution

Detailed explanation

\(x = 10 - 2y\) \(P = x^2 y^3 = (10 - 2y)^2 y^3\) \(\frac{dP}{dy} = 10y^2(10-2y)(3-y) = 0\) \(y = 3\) (since \(x, y > 0\)) \(x = 10 - 2(3) = 4\) \(x^2 + 2y^3 = 4^2 + 2(3^3) = 16 + 2(27) = 16 + 54 = 70\)