Mathematics · Hyperbola

JEE Main 2026 — 6 April, Morning Shift — Question 23

Let e₁ and e₂ be two distinct roots of the equation x2−ax+2=0.x² - ax + 2 = 0. Let the sets {a∈R:e1a∈R: e_1 and e2e_2 are the eccentricities of hyperbolas}=(α,β), = (α,β), and {a∈R:e1a∈R: e_1 and e2e_2 are the eccentricities of an ellipse and a hyperbola, respectively} =(γ,∞).= (γ,∞). Then α2+β2+γ2α²+β²+γ² is equal to :

  1. Option A:

    1818

  2. Option B:

    2222

  3. Option C:

    2626

    Correct
  4. Option D:

    3434

Answer: C

Step-by-step solution

e1+e2=ae_{1}+e_{2}=a e1e2=2⇒e2=2e1e_{1} e_{2}=2 \Rightarrow e_{2}=\frac{2}{e_{1}} Case 1 : Both are eccentricities of hyperbola Now, e1>1\mathrm{e}_{1}>1 and e2>1\mathrm{e}_{2}>1 ⇒2e1>1⇒e1<2⇒e1∈(1,2)\Rightarrow \frac{2}{\mathrm{e}_{1}}>1 \Rightarrow \mathrm{e}_{1}<2 \Rightarrow \mathrm{e}_{1} \in(1,2) Now, a=e1+1e1\mathrm{a}=\mathrm{e}_{1}+\frac{1}{\mathrm{e}_{1}} Minimum occurs at e1=2\mathrm{e}_{1}=\sqrt{2} ⇒amin =22\Rightarrow \mathrm{a}_{\text {min }}=2 \sqrt{2} if e=1,2\mathrm{e}=1,2 (end points) a→2,3⇒a∈(22,3)\mathrm{a} \rightarrow 2,3 \Rightarrow \mathrm{a} \in(2 \sqrt{2}, 3) ⇒α=22\Rightarrow \alpha=2 \sqrt{2} and β=3\beta=3 Case 2 : One ellipse, one hyperbola

(e1)0<e1<1 and e2<1e2=2e1>2\begin{aligned} & \left(\mathrm{e}_{1}\right) \\& 0<\mathrm{e}_{1}<1 \text { and } \mathrm{e}_{2}<1 \\& \mathrm{e}_{2}=\frac{2}{\mathrm{e}_{1}}>2 \end{aligned}

Now a=e1+2e1\mathrm{a}=\mathrm{e}_{1}+\frac{2}{\mathrm{e}_{1}} as e1→1⇒a→3\mathrm{e}_{1} \rightarrow 1 \Rightarrow \mathrm{a} \rightarrow 3 e1→0⇒a→∞\mathrm{e}_{1} \rightarrow 0 \Rightarrow \mathrm{a} \rightarrow \infty ∴(3,∞)⇒r=3\therefore(3, \infty) \Rightarrow \mathrm{r}=3 Now α2+β2+γ2=8+9+9=26\alpha^{2}+\beta^{2}+\gamma^{2}=8+9+9=26

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Hyperbola
Topic
Introduction to Hyperbola