1.

\( \operatorname{5tan}^{-1}(x)+3 \cot ^{-1}(x)=\frac{7 \pi}{4} \)

Answer»

5 tan-1x + 3 cot-1x = \(\frac{7\pi}4\)

⇒ 2 tan-1x + 3(tan-1x + cot-1x) = \(\frac{7\pi}4\)

⇒ 2 tan-1x + \(\frac{3\pi}2\) = \(\frac{7\pi}4\)

⇒ 2 tan-1x = \(\frac{7\pi}4\) - \(\frac{3\pi}2\) = \(\frac{7\pi-5\pi}4=\frac{\pi}4\)

⇒ tan-1x = \(\frac{\pi}8\)

⇒ x = tan\((\frac{\pi}8)\) ≅ 0.414
 



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