Let α , β be the roots of the equation x 2 - 2 x + 6 = 0 and 1 α 2 + 1 , 1 β 2 + 1 be…

Let α,β be the roots of the equation x2-2x+6=0 and 1α2+1,1β2+1 be the roots of the equation x2+ax+b=0. Then the roots of the equation x2-a+b-2x+a+b+2=0 are :
  1. non-real complex numbers
  2. real and both negative
  3. real and both positive
  4. real and exactly one of them is positive

Solution

Given α,β be the roots of the equation x2-2x+6=0 

So sum of roots will be α+β=2 and product of roots will be αβ=6

And also given 1α2+1 and 1β2+1 are roots of x2+ax+b=0

So sum of roots will be -a=1α2+1+1β2+1

a=-1α2-1β2-2 .....1

And similarly product of roots will be,

b=1α2+1β2+1+1α2β2 ....2

Now adding equation 1 & 2 we get,

a+b=1αβ2-1=16-1=-56 {as αβ=6}

Now putting the value of a+b in x2-a+b-2x+a+b+2=0

x2--56-2x+2-56=0

6x2+17x+7=0

x=-73,x=-12 are the roots, both roots are real and negative.

Asked in: JEE Main 2022 (28 Jul Shift 2)

Practice more Quadratic Equation questions on Aicharya