Question

The expression: (shown below) where u = g(x) and du = g'(x)dx, represents:

Answer 1

another form of the First Fundamental Theorem of Calculus.
another form of the Second Fundamental Theorem of Calculus.
a clever approach to solving antiderivative problems.
the method of substitution (or change of variables) for differential equations.
the method of substitution (or change of variables) for definite integrals.

Answer 2

@perl

Answer 3

@amorfide