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2. Polynomials
easy
निम्नलिखित गुणनफल ज्ञात कीजिए
$\left(\frac{x}{2}+2 y\right)\left(\frac{x^{2}}{4}-x y+4 y^{2}\right)$
Option A
Option B
Option C
Option D
Solution
$\left(\frac{x}{2}+2 y\right)\left(\frac{x^{2}}{4}-x y+4 y^{2}\right)=\left(\frac{x}{y}+2 y\right)\left\{\left(\frac{x}{2}\right)^{2}-\left(\frac{x}{2}\right)(2 y)+(2 y)^{2}\right\}$
$=\left(\frac{x}{2}\right)^{3}+(2 y)^{3} \quad\left[\because(a+b)\left(a^{2}-a b+b^{2}\right)=a^{3}+b^{3}\right]$
$=\frac{x^{3}}{8}+8 y^{3}$
Standard 9
Mathematics