The product of the roots of the
equation 9x2 - 18|x| + 5 = 0 is :
Solution
$9{x^2} - 18\left| x \right| + 5 = 0$<br><br>$\Rightarrow$ $9{x^2} - 15\left| x \right| - 3\left| x \right| + 5 = 0$ ($\because$ x<sup>2</sup> = ${\left| x \right|^2}$)<br><br>$\Rightarrow$ $3\left| x \right|(3\left| x \right| - 5) - (3\left| x \right| - 5) = 0$<br><br>$\Rightarrow$$\left| x \right| = {1 \over 3},\,{5 \over 3}$<br><br>$\Rightarrow$ $x = \pm {1 \over 3}, \pm \,{5 \over 3}$<br><br>$\therefore$ Product of roots <br><br>= $$\left( \frac{1}{3} \right) \left( -\frac{1}{3} \right) \left( \frac{5}{3} \right) \left( -\frac{5}{3} \right) $$
= ${{25} \over {81}}$
About this question
Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Complex Numbers and Argand Plane
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