$\( \left(\frac{x}{2}+\frac{3 y}{4}\right)\left(\frac{x}{2}+\frac{3 y}{4}\right) \)
已知:$\left(\frac{x}{2} \ +\ \frac{3y}{4}\right) \ \times \ \left(\frac{x}{2} \ +\ \frac{3y}{4}\right)$
求解:我们需要求$\left(\frac{x}{2} \ +\ \frac{3y}{4}\right) \ \times \ \left(\frac{x}{2} \ +\ \frac{3y}{4}\right)$的值。
解:
$\left(\frac{x}{2} \ +\ \frac{3y}{4}\right) \ \times \ \left(\frac{x}{2} \ +\ \frac{3y}{4}\right)$
= $\left(\frac{x}{2} \ +\ \frac{3y}{4}\right)^{2}$
= $\left(\frac{x}{2}\right)^{2} \ +\ \left(\frac{3y}{4}\right)^{2} +2\times \left(\frac{x}{2}\right) \times \left(\frac{3y}{4}\right) \ $
= $\frac{x^2}{4} \ +\frac{9y^2}{16} +\frac{3xy}{4} \ $
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