Practicing Success
The number of solutions of $sin \begin{Bmatrix} sin^{-1}\left(log_{1/2}x\right)\end{Bmatrix} + 2\begin{vmatrix}cos \begin{Bmatrix}sin^{-1}\left(\frac{x}{2}-\frac{3}{2}\right)\end{Bmatrix}\end{vmatrix}=0$, is |
1 2 3 none of these |
2 |
The two terms on the LHS of the given equation are meaningful, if $-1 ≤ log_{1/2}x ≤ 1 $ and $ -1 ≤ \frac{x}{2}-\frac{3}{2}≤1$ $⇒ 2 ≥ x ≥ \frac{1}{2}$ and $ 1 ≤ x ≤ 5 ⇒ 1 ≤ x ≤ 2 $ Now, $1 ≤ x ≤ 2 $ $⇒ \frac{1}{2}≤ \frac{x}{2} ≤1$ $⇒ -\frac{1}{2}≤ \frac{x}{2}-1 ≤0$ $⇒ -\frac{\pi}{6} ≤ siN^{-1} \left(\frac{x}{2}-1\right) ≤ 0$ $⇒ \frac{\sqrt{3}}{2}≤ cos \begin{Bmatrix}sin^{-1}\left(\frac{x}{2}-1\right)\end{Bmatrix}≤1$ $⇒ \sqrt{3} ≤2 cos \begin{Bmatrix}sin^{-1}\left(\frac{x}{2}-1\right)\end{Bmatrix}≤2$ $⇒ \sqrt{3} ≤2 cos \begin{vmatrix}sin^{-1}\left(\frac{x}{2}-1\right)\end{vmatrix}≤2$ Again, $1 ≤x ≤2$ $⇒ -1 ≤ log_{1/2}x ≤ 0 $ $⇒ -\frac{\pi}{2} ≤ sin^{-1}(log_{1/2}x) ≤ 0 $ $⇒ -1 ≤ \begin{Bmatrix}sin^{-1}(log_{1/2} x)\end{Bmatrix}≤ 0 $ $⇒ \sqrt{3}-1 ≤sin \begin{Bmatrix}sin^{-1} (log_{1/2}) x\end{Bmatrix} + \begin{vmatrix}cos \, sin^{-1}\left(\frac{x}{2}-\frac{3}{2}\right)\end{vmatrix} ≤ 2$ $⇒ sin \begin{Bmatrix}sin^{-1}(log_{1/2} x)\end{Bmatrix}+ 2\begin{vmatrix} cos \begin{Bmatrix} sin^{-1}\left(\frac{x}{2}-\frac{3}{2}\right) \end{Bmatrix}\end{vmatrix}$ ≠ 0 for any x. Hence, the given equations has no solution. |