Evaluate (2x7−7y4)2\Big(\dfrac{2x}{7} - \dfrac{7y}{4}\Big)^2(72x−47y)2
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Solving,
⇒(2x7−7y4)2⇒(2x7)2+(7y4)2−2×2x7×7y4⇒4x249+49y216−xy.\Rightarrow \Big(\dfrac{2x}{7} - \dfrac{7y}{4}\Big)^2 \\[1em] \Rightarrow \Big(\dfrac{2x}{7}\Big)^2 + \Big(\dfrac{7y}{4}\Big)^2 - 2 \times \dfrac{2x}{7} \times \dfrac{7y}{4} \\[1em] \Rightarrow \dfrac{4x^2}{49} + \dfrac{49y^2}{16} - xy.⇒(72x−47y)2⇒(72x)2+(47y)2−2×72x×47y⇒494x2+1649y2−xy.
Hence, (2x7−7y4)2=4x249+49y216−xy.\Big(\dfrac{2x}{7} - \dfrac{7y}{4}\Big)^2 = \dfrac{4x^2}{49} + \dfrac{49y^2}{16} - xy.(72x−47y)2=494x2+1649y2−xy.
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