Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Quadratic Equation and Inequalities question

2023 · 30 Jan · Shift 2 · Q39
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Mathematics
  4. /Quadratic Equation and Inequalities
  5. /2023 · 30 Jan · Shift 2 · Q39

Quadratic Equation and Inequalities question

2023 · 30 Jan · Shift 2 · Q39

JEE MainMathematicsQuadratic Equation and InequalitiesNumerical+4 / −1
If the value of real number a>0a\gt 0a>0 for which x2−5ax+1=0x^2-5 a x+1=0x2−5ax+1=0 and x2−ax−5=0x^2-a x-5=0x2−ax−5=0 have a common real root is 32β\frac{3}{\sqrt{2 \beta}}2β​3​ then β\betaβ is equal to ‾\underline{\hspace{2cm}}​.
Numerical answer
View written solutionFree

Correct answer: 13

  1. Let the common real root of x2−5ax+1=0andx2−ax−5=0x^2-5ax+1=0 \quad \text{and} \quad x^2-ax-5=0x2−5ax+1=0andx2−ax−5=0 be rrr.

  2. Since rrr satisfies both equations, r2−5ar+1=0...(1)r^2-5ar+1=0 \qquad ...(1)r2−5ar+1=0...(1) r2−ar−5=0...(2)r^2-ar-5=0 \qquad ...(2)r2−ar−5=0...(2)

  3. Subtract (2) from (1): (r2−5ar+1)−(r2−ar−5)=0\left(r^2-5ar+1\right)-\left(r^2-ar-5\right)=0(r2−5ar+1)−(r2−ar−5)=0 −4ar+6=0-4ar+6=0−4ar+6=0 4ar=64ar=64ar=6 ar=32ar=\frac{3}{2}ar=23​

  4. Now use this in one of the equations, say (2): r2−ar−5=0r^2-ar-5=0r2−ar−5=0 r2−32−5=0r^2-\frac{3}{2}-5=0r2−23​−5=0 r2=132r^2=\frac{13}{2}r2=213​

  5. Since a>0a>0a>0 and ar=32>0ar=\frac{3}{2}>0ar=23​>0, we must have r>0r>0r>0. Hence r=132r=\sqrt{\frac{13}{2}}r=213​​

  6. Now a=32r=3213/2a=\frac{3}{2r}=\frac{3}{2\sqrt{13/2}}a=2r3​=213/2​3​ Simplify: a=326a=\frac{3}{\sqrt{26}}a=26​3​

  7. Given a=32βa=\frac{3}{\sqrt{2\beta}}a=2β​3​ compare with a=326a=\frac{3}{\sqrt{26}}a=26​3​ so, 2β=262\beta=262β=26 β=13\beta=13β=13

  8. Therefore, the required integer is 13\boxed{13}13​

PreviousNext

More from Quadratic Equation and Inequalities

  • The number of real roots of the equation x2−4x+3​+x2−9​=4x2−14x+6​, is :2023 · MCQ
  • The equation e4x+8e3x+13e2x−8ex+1=0,x∈R has :2023 · MCQ
  • If the sum of the squares of the reciprocals of the roots α and β of the equation 3x2 +λ x − 1 = 0 is 15, then 6(α 3 + β 3)2 is equal to :2022 · MCQ
  • The sum of all the real roots of the equation (e2x−4)(6e2x−5ex+1)=0 is2022 · MCQ
  • The number of distinct real roots of the equation x7 − 7x − 2 = 0 is2022 · MCQ
  • If α,β,γ,δ are the roots of the equation x4+x3+x2+x+1=0, then α2021+β2021+γ2021+δ2021 is equal to :2022 · MCQ
  • Let A={x∈R:∣x+1∣<2} and B={x∈R:∣x−1∣≥2}. Then which one of the following statements is NOT true?2022 · MCQ
  • Let a, b ∈ R be such that the equation ax2−2bx+15=0 has a repeated root α. If α and β are the roots of the equation x2−2bx+21=0, then α2+β2 is equal to :2022 · MCQ