AP EAMCET2013MathematicsQuadratic Equation

If the harmonic mean between the roots of (5+ 2 ) x^2-b x+(8+2 5 )=0 is 4 , then the value of b is

Options

A2
B3
C4- 5
D4+ 5

Correct answer

D. 4+ 5

Step-by-step solution

Given equation is (5+ 2 ) x^2-b x+(8+2 5 )=0 Let and be the roots of this equation. aligned + & = b 5+ 2 & = 8+2 3 5+ 2 aligned Given that harmonic mean between the roots of the given equation is 4 . array rr & 2 + =4 & 8+2 5 5+ 2 5+ 2 b =2 & b= 8+2 5 2 & =4+ 5 array

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