Integral Calculus Khan Academy

Practice this lesson yourself on khanacade. Integral (or antiderivative) 1/x should be a. Using definite integral to solve a word problem about the growth in population of town.

Worked example of finding an indefinite integral where integration by parts is applied twice. Integration goes other way. Since definite integrals are the net area between a curve and xaxis, we can sometimes use geometric formulas to find integrals.

But what if itself is below xaxis. To find it exactly, we can divide into infinite rectangles infinitely smal. In differential calculus we learned that the derivative of ln(x) is 1/x.