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AP EAMCET · Maths · Application of Derivatives

Find the minimum value of 2 x+3 y when xy=6.

  1. A 9
  2. B 12
  3. C 8
  4. D 6
Verified Solution

Answer & Solution

Correct Answer

(B) 12

Step-by-step Solution

Detailed explanation

Given: xy=6 ⇒y=6x ⇒fx,y=2x+3y ⇒fx=2x+3×6x ⇒fx=2x+18x ⇒f'x=2-18x2 Put f'x=0 for maximum or minimum ⇒0=2-18x2 ⇒x2=9 ⇒x=±3 ⇒f''x=0--18×2x3 ⇒f''3=3633>0 ⇒f''(3)>0 At x=3 ,fx is minimum The…