If (2x 2 -3x+1)(2x 2 +5x+1) =9x 2 , then eqn has a) Four real roots b) Two real and two imaginary c) Four imaginary roots d) none

If  (2x2-3x+1)(2x2+5x+1) =9x2, then eqn has

a)     Four real roots

b)    Two real and two imaginary

c)     Four imaginary roots

d)    none


1 Answers

jitender lakhanpal
62 Points
12 years ago

Dear pooja, 

correct option is a)



(2x2-3x+1)(2x2+5x+1) =9x2

divide the equation by x^2 where x not equal to 0

(2x-3+1/x)(2x+5+1/x) = 9

 let  2x+1/x = y  put in the equation 

(y-3)(y+5) = 9

y2+2 y - 24 = 0 

solving the equation we get  y = -6 and y = 4 

so we get   

 2x+1/x = -6        and 

 2x+1/x = 4      we get 

2x2+6x+1=0    finding discriminant we get it as  +ve so 2 real roots  

2x2-4x+1=0 and again finding discriminant we get it as +ve so 2 real roots   so the total of 4 real roots 







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