The function is
and the point is
.
The function is in the form of composite function
.
Assume
and
.
Consider
.
Differentiate on each side with respect to
.

Consider
.
Differentiate on each side with respect to
.

.
Chain Rule of derivatives:
.
Substitute
and
in chain rule.

Slope of the tangent is derivative of the function.
\
.
Slope of the tangent line at
.

Slope of the tangent line is
.
Point-slope form of line equation
.
Substitute slope
and the point
.

The equation of a tangent line
.