Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
BITSAT 2016
Exam
BITSAT
Year
2016
Subject
Mathematics
Chapter
Quadratic Equation

BITSAT 2016 · Mathematics · Quadratic Equation

If α, β are the roots of the equations x^ 2 -2 x-1=0, then what is...

If α,β\alpha, \beta are the roots of the equations x2−2x−1=0,x^{2}-2 x-1=0, then what is the value of α2β−2+α−2β2\alpha^{2} \beta^{-2}+\alpha^{-2} \beta^{2}

Options

  1. A-2
  2. B0
  3. C30
  4. D34

Correct answer

D. 34

Step-by-step solution

Since, (\alpha) and (\beta) are the roots of the equation x2−2x−1=0x^{2}-2 x-1=0, then Sum of roots, (\alpha+\beta=2) and product of the roots (\alpha \beta=-1) Since, ((\alpha+\beta)=\alpha^{2}+\beta^{2}+2 \alpha \beta) (\Rightarrow 4=\alpha^{2}+\beta^{2}-2) (\Rightarrow \alpha^{2}+\beta^{2}=6) Now, (\alpha^{2} \beta^{-2}+\alpha^{-2} \beta^{2}=\frac{\alpha^{2}}{\beta^{2}}+\frac{\beta^{2}}{\alpha^{2}}=\frac{\alpha^{4}+\beta^{4}}{(\alpha \beta)^{2}}(⇒(α2+β2)2=(\Rightarrow\left(\alpha^{2}+\beta^{2}\right)^{2}=6^{2}) (\Rightarrow \alpha^{4}+\beta^{4}+2 \alpha^{2} \beta^{2}=36) (\Rightarrow \alpha^{4}+\beta^{4}+2=36) (\Rightarrow \alpha^{4}+\beta^{4}=34 \ldots..(i)(\mathrm{i}) (\Rightarrow α4+β4(αβ)2=34(−1)2=\frac{\alpha^{4}+\beta^{4}}{(\alpha \beta)^{2}}=\frac{34}{(-1)^{2}}=34) [Putting value of (\alpha^{4}+\beta^{4}=34) from Equation (i) ]]
Practice Quadratic Equation on Quantrex Academy →

More from Quadratic Equation

Roots of the equation x^2+b x-c=0(b, c>0) are BITSAT 2024Rational roots of the equation 2 x^4+x^3-11 x^2+x+2=0 are BITSAT 2024If 15^ ^ ∘ and 30^ ^ ∘ are the roots of the equation x^2+p x+q=0 , then p q= BITSAT 2024The roots of the given equation (p-q) x^2+(q-r) x+(r-p)=0 are : BITSAT 2023Solve 5 x^2+x+ 5 =0 BITSAT 2023The roots of the given equation (p-q) x^2+(q-r) x+(r-p)=0 are : BITSAT 2023The range of the function f(x)= 3 x^2-4 x+5 is BITSAT 2023Solution of 2^x+2^ |x| ≥ 2 2 is BITSAT 2023If one root of the equation x^2+p x+12=0 is 4, while the equation x^2+p x+q=0 . has equal… BITSAT 2023If α be a root of the equation 4 x^2+2 x-1=0 , then the other root of the equation is BITSAT 2022Let a, b be the solutions of x^2+p x+1=0 and c, d be the solution of x^2+q x+1=0 . If… BITSAT 2022Find the value of a such that the sum of the squares of the roots of the equation x^ 2… BITSAT 2021The number of real solutions of the equation (x-1)^ 2 +(x-2)^ 2 +(x-3)^ 2 =0 is BITSAT 2020In the real number system, the equation x + 3 - 4 x - 1 + x + 8 - 6 x - 1 = 1 has BITSAT 2019Let p and q be roots of the equation x^ 2 - 2x + A = 0 and let r and s be the roots of… BITSAT 2019If x, y, z ∈ ℝ, x + y + z = 5, x^ 2 + y^ 2 + z^ 2 = 9 , then length of interval in which… BITSAT 2019 Full Quadratic Equation list Quadratic Equation JEE Maths PYQsJEE Mathematics PYQs All BITSAT PYQs