Skip to main content

Let α and β be the roots of the equation x^2-x-1=0 . If _k=(α )^k+(β )^k,k≥ 1, then which one of the following statements is not true?

JEE Main 2020 — Mathematics Algebra

2020mcqhard

Let α\alphaα and β\betaβ be the roots of the equation x2−x−1=0{x}^{2}-x-1=0x2−x−1=0 . If pk=(α)k+(β)k,k≥1,{p}_{k}={(\alpha )}^{k}+{(\beta )}^{k},k\geq 1,pk​=(α)k+(β)k,k≥1, then which one of the following statements is not true?

Official previous-year question

Held on 7 Jan 2020 · Verified 6 Jul 2026.

Options

  1. A

    p3=p5−p4{p}_{3}={p}_{5}-{p}_{4}p3​=p5​−p4​

  2. B

    p5=11{p}_{5}=11p5​=11

  3. C

    (p1+p2+p3+p4+p5)=26({p}_{1}+{p}_{2}+{p}_{3}+{p}_{4}+{p}_{5})=26(p1​+p2​+p3​+p4​+p5​)=26

  4. D

    p5=p2⋅p3{p}_{5}={p}_{2}\cdot {p}_{3}p5​=p2​⋅p3​

Did you get this right?

Sign in to track your attempts and accuracy.

Your note

Sign in to keep a private note on this question. Nothing you write is ever public.

JEE Main Algebra in other years

More JEE Main Algebra questions

If the quadratic equation $(\lambda+2)x^2-3\lambda x+4\lambda=0$, $\lambda \neq -2$, has two positive roots, then the number of possible integral values of $\lambda$ is:

2026medium

The value of $\frac{{ }^{100} \mathrm{C}_{50}}{51}+\frac{{ }^{100} \mathrm{C}_{51}}{52}+\ldots.+\frac{{ }^{100} \mathrm{C}_{100}}{101}$ is :

2026medium

Let $e_1$ and $e_2$ be two distinct roots of the equation $x^2 - ax + 2 = 0$. Let the sets $\{a \in \mathbb{R} : e_1 \text{ and } e_2 \text{ are the eccentricities of hyperbolas}\} = (\alpha, \beta)$, and $\{a \in \mathbb{R} : e_1 \text{ and } e_2 \text{ are the eccentricities of an ellipse and a hyperbola, respectively}\} = (\gamma, \infty)$. Then $\alpha^2 + \beta^2 + \gamma^2$ is equal to:

2026hard

Among the statements : I: If $\left|\begin{array}{ccc}1 & \cos \alpha & \cos \beta \\ \cos \alpha & 1 & \cos \gamma \\ \cos \beta & \cos \gamma & 1\end{array}\right|=\left|\begin{array}{ccc}0 & \cos \alpha & \cos \beta \\ \cos \alpha & 0 & \cos \gamma \\ \cos \beta & \cos \gamma & 0\end{array}\right|$, then $\cos ^{2} \alpha+\cos ^{2} \beta+\cos ^{2} \gamma=\frac{3}{2}$, and II : If $\left|\begin{array}{ccc}x^{2}+x & x+1 & x-2 \\ 2 x^{2}+3 x-1 & 3 x & 3 x-3 \\ x^{2}+2 x+3 & 2 x-1 & 2 x-1\end{array}\right|=\mathrm{p} x+\mathrm{q}$, then $\mathrm{p}^{2}=196 \mathrm{q}^{2}$,

2026hard

If $\left(\frac{1}{{ }^{15} \mathrm{C}_{0}}+\frac{1}{{ }^{15} \mathrm{C}_{1}}\right)\left(\frac{1}{{ }^{15} \mathrm{C}_{1}}+\frac{1}{{ }^{15} \mathrm{C}_{2}}\right) \cdots\left(\frac{1}{{ }^{15} \mathrm{C}_{12}}+\frac{1}{{ }^{15} \mathrm{C}_{13}}\right)=\frac{\alpha^{13}}{{ }^{14} \mathrm{C}_{0}{ }^{14} \mathrm{C}_{1} \cdots{ }^{14} \mathrm{C}_{12}}$, then $30 \alpha$ is equal to $\_\_\_\_$.

2026medium

Other Mathematics topics for JEE Main

Keep practicing Algebra

Work through every JEE Main Algebra PYQ, year by year.

Browse all Mathematics topics