`tan3A-tan2A-tanA=`
`a. tan3A tan2A tanA, b.-tan3A tan2A tanA, c.tanAtan2A-tanAtan3A-tan2Atan3A, d.`none of these

Explanation

To solve the equation \( \tan 3A - \tan 2A - \tan A = ? \), we can use the tangent addition formula. The formula for the tangent of the sum of two angles is given by:

\[ \tan(x + y) = \frac{\tan x + \tan y}{1 - \tan x \tan y} \]

### Step 1: Express \(\tan 3A\)
We can express \(\tan 3A\) using the tangent addition formula:
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