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JEE Advanced 2026 · Complex Numbers and Quadratic Equations

Match each entry in List-I to the correct entry in List-II and choose the correct option. | List-I | List-II | | --- | --- | | (P) If α\alpha and β\beta are the distinct roots of the equation x2+x+1=0x^{2} + x + 1 = 0, then the quadratic equation with roots 1(α+1)2026\frac{1}{(\alpha+1)^{2026}} and 1(β+1)2026\frac{1}{(\beta+1)^{2026}} is | (1) x2+x+1=0x^{2} + x + 1 = 0 | | (Q) If α\alpha and β\beta are the distinct roots of the equation x2+x+1=0x^{2} + x + 1 = 0, then the quadratic equation with roots 1(α+1)2027\frac{1}{(\alpha+1)^{2027}} and 1(β+1)2027\frac{1}{(\beta+1)^{2027}} is | (2) x2−x+1=0x^{2} - x + 1 = 0 | | (R) If γ\gamma and δ\delta are the distinct roots of the equation x2−x+1=0x^{2} - x + 1 = 0, then the value of 1(γ−1)2026+1(δ−1)2026\frac{1}{(\gamma-1)^{2026}} + \frac{1}{(\delta-1)^{2026}} is | (3) x2+x−1=0x^{2} + x - 1 = 0 | | (S) If p and r are the distinct roots of the equation x2+x−1=0x^{2} + x - 1 = 0, then the value of 1(p+1)3+1(r+1)3\frac{1}{(p+1)^{3}} + \frac{1}{(r+1)^{3}} is | (4) −1-1 | | | (5) −4-4 |

Answer: C. (P) →\to (1), (Q) →\to (2), (R) →\to (4), (S) →\to (5)

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Written solution

(P),(Q): roots of x2+x+1=0\text{(P),(Q): roots of } x^{2}+x+1=0

(R): roots of x2−x+1=0\text{(R): roots of } x^{2}-x+1=0

(S): roots of x2+x−1=0\text{(S): roots of } x^{2}+x-1=0

To find: match (P),(Q),(R),(S) with (1)–(5)\text{To find: match (P),(Q),(R),(S) with (1)--(5)}

α2+α+1=0⇒α+1=−α2,α3=1\alpha^{2}+\alpha+1=0 \Rightarrow \alpha+1 = -\alpha^{2}, \quad \alpha^{3}=1

(α+1)2026=(−α2)2026=α4052=α2(\alpha+1)^{2026} = (-\alpha^{2})^{2026} = \alpha^{4052} = \alpha^{2}

1(α+1)2026=1α2=α\frac{1}{(\alpha+1)^{2026}} = \frac{1}{\alpha^{2}} = \alpha

Roots: α, β⇒x2+x+1=0\text{Roots: } \alpha,\ \beta \Rightarrow x^{2}+x+1=0

(P)→(1)(P)\to(1)

(α+1)2027=(−α2)2027=−α4054=−α(\alpha+1)^{2027} = (-\alpha^{2})^{2027} = -\alpha^{4054} = -\alpha

1(α+1)2027=−1α=−α2\frac{1}{(\alpha+1)^{2027}} = -\frac{1}{\alpha} = -\alpha^{2}

Sum =−(α2+β2)=−(−1)=1\text{Sum } = -(\alpha^{2}+\beta^{2}) = -(-1) = 1

Product =(αβ)2=1\text{Product } = (\alpha\beta)^{2} = 1

x2−x+1=0⇒(Q)→(2)x^{2}-x+1=0 \Rightarrow (Q)\to(2)

γ2−γ+1=0⇒γ−1=γ2,γ3=−1, γ6=1\gamma^{2}-\gamma+1=0 \Rightarrow \gamma-1 = \gamma^{2}, \quad \gamma^{3}=-1,\ \gamma^{6}=1

(γ−1)2026=γ4052=γ2(\gamma-1)^{2026} = \gamma^{4052} = \gamma^{2}

1(γ−1)2026=γ4\frac{1}{(\gamma-1)^{2026}} = \gamma^{4}

γ4+δ4=(γ2+δ2)2−2(γδ)2\gamma^{4}+\delta^{4} = (\gamma^{2}+\delta^{2})^{2}-2(\gamma\delta)^{2}

=(−1)2−2(1)=−1⇒(R)→(4)= (-1)^{2}-2(1) = -1 \Rightarrow (R)\to(4)

p2+p−1=0,q=p+1p^{2}+p-1=0, \quad q = p+1

q2−q−1=0q^{2}-q-1=0

q2=q+1,1q=q−1q^{2}=q+1,\quad \frac{1}{q}=q-1

1q3=(q−1)3=2q−3\frac{1}{q^{3}} = (q-1)^{3} = 2q-3

1(p+1)3+1(r+1)3=2(q1+q2)−6\frac{1}{(p+1)^{3}}+\frac{1}{(r+1)^{3}} = 2(q_1+q_2)-6

q1+q2=1⇒=−4⇒(S)→(5)q_1+q_2 = 1 \Rightarrow = -4 \Rightarrow (S)\to(5)

(P)→(1), (Q)→(2), (R)→(4), (S)→(5)(P)\to(1),\ (Q)\to(2),\ (R)\to(4),\ (S)\to(5)

Option (3)\text{Option } (3)

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