Detailed description
y = f(x) of f(x) = x squared + 1, parabola, region from x = a to point on x axis marked as x shaded between parabola and x axis, this area labelled as A(x). A vertical line from the x axis to the graph at x = b.
Integration
y = f(x) of f(x) = x squared + 1, parabola, region from x = a to point on x axis marked as x shaded between parabola and x axis, this area labelled as A(x). A vertical line from the x axis to the graph at x = b.