If the function [math]f[/math] is continuous at every point of the interval [math][a,b][/math] and may cross the [math]x[/math]-axis at a finite number of points in the interval. Let [math]P^+[/math] and [math]P^-[/math] have their usual meaning [as in formula].
- Is [math]|f(x)|[/math] continuous at every point of [math][a,b][/math]?
- Show that
[[math]] \mbox{''area''}(P^+ \cup P^-) = \int_a^b |f(x)| \; dx . [[/math]]
Find the area of the region bounded by the parabola [math]y = x^2[/math], the [math]x[/math]-axis, and the line tangent to the parabola at the point [math](2, 4)[/math]. Do the problem
- using [math]x[/math] as the variable of integration.
- using [math]y[/math] as the variable of integration.
Do Problem Exercise for the line tangent to the parabola at the general point [math](a, a^2)[/math].
Express the area of the ellipse [math]\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1[/math] as a definite integral of a function of [math]x[/math], and as a definite integral of a function of [math]y[/math]. (The resulting indefinite integrals cannot be evaluated with the theory so far developed.)
Find the area of the shaded region in Figure. The curves are parabolas. The inscribed square has area [math]4[/math], and the circumscribed square has area [math]16[/math].