Simplify

(tan 4X+tan 2x)/(1-(tan 4X)(tan2X))

This is clearly tan(4x+2x) = tan(6x)

To simplify the expression, we can make use of the trigonometric identity:

tan(A + B) = (tan A + tan B) / (1 - tan A * tan B)

In this case, A = 4X and B = 2X, so we can rewrite the expression as:

(tan 4X + tan 2X) / [1 - (tan 4X)(tan 2X)]

Now, we can substitute A and B into the identity:

tan(4X + 2X) = (tan 4X + tan 2X) / [1 - (tan 4X)(tan 2X)]

Simplifying further:

(tan 6X) / [1 - (tan 4X)(tan 2X)]

Therefore, the simplified expression is (tan 6X) / [1 - (tan 4X)(tan 2X)].