What is the area under the linear function f(x) = 2x from x = 0 to x = 3?

Approximate the area under the curve of f(x) = x^2 from x = 0 to x = 4 using 4 rectangles with left endpoints.

What is the base of each rectangle when approximating the area under the curve from x = 1 to x = 5 using 4 rectangles?

If the left endpoint approximation of the area under f(x) = x^2 from x = 0 to x = 3 is 5.5 and the right endpoint approximation is 14.5, what can be said about the true area?

Using the limit definition, find the exact area under the curve of f(x) = 4x from x = 0 to x = 3.