Question

How do you find the exact value of `tan(tan^-1(-4.2))`?

Answer 1

The value of given expression is `-4.2`

Explanation:

If a function `f(x)` has its inverse function `f^-1(x)`, then the value of:

`f(f^-1(a))` or `f^-1(f(a))` is `a`.

In the given example `a=-4.2`