Medium INTEGER +4 / -1 PYQ · JEE Mains 2023

If the value of real number $a>0$ for which $x^2-5 a x+1=0$ and $x^2-a x-5=0$

have a common real root is $\frac{3}{\sqrt{2 \beta}}$ then $\beta$ is equal to ___________.

Answer (integer) 13

Solution

<p>${x^2} - 5\alpha x + 1 = 0$ ..... (1)</p> <p>${x^2} - \alpha x - 5 = 0$ ...... (2)</p> <p>have a common root.</p> <p>Subtracting (1) with (2) we'll get $x = {6 \over {4\alpha }}$</p> <p>Substituting in (1)</p> <p>${{36} \over {16{\alpha ^2}}} - {{30} \over 4} + 1 = 0$</p> <p>$\Rightarrow {\alpha ^2} = {9 \over {26}}$</p> <p>$\alpha = {3 \over {\sqrt {2 \times 13} }}$</p> <p>$\therefore$ $\beta = 13$</p>

About this question

Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Complex Numbers and Argand Plane

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