Practicing Success
If $\tan^{-1}(-3x)+\tan^{-1}(-2x)=\frac{π}{4}$, then the values of $x$ are |
$-1,\frac{-1}{6}$ $-1,\frac{1}{16}$ $\frac{-1}{6}$ $1,\frac{1}{6}$ |
$\frac{-1}{6}$ |
$\tan^{-1}(-3x)+\tan^{-1}(-2x)=\frac{π}{4}$ $=\tan^{-1}\left(\frac{-3x-2x}{1-(-3x)(-2x)}\right)=\frac{π}{4}$ $\left[∵\tan^{-1}(a)+\tan^{-1}(b)=\tan^(\frac{a+b}{ 1- ab})\right] a>0,b>0 , a.b<1$ applying $\tan$ on both side we get $\frac{-5x}{1-6x^2}=1$ $[∵\tan\frac{π}{4}=1]$ so $-5x=1-6x^2$ $⇒6x^2-5x-1=0$ $⇒6x^2-6x+x-1=0$ $⇒6x(x-1)+1(x-1)=0$ $⇒(6x+1)(x-1)=0$ $⇒x=1,\frac{-1}{6}$ $\text{ only } x= \frac{-1}{6} \text{ Satisfy the condition}$ |