How to Solve Integrals With Square Roots of Quadratic Equations in Both the Numerator & Denominator

Not all integrals can be integrated. This includes many integrals with square roots of quadratic equations in both the numerator and denominator. If you find this problem in a homework or textbook problem, you can safely assume it can be integrated. You will have to "get lucky" in finding that the same substitution enables you to simplify the square root in both the top and the bottom. Before attempting this problem, you should know how to complete the square, use "u" and "trig" substitutions, integrate by parts and use integral tables.

Instructions

    • 1

      Complete the square on both the numerator and the denominator. It is possible that one or both of these may actually be a perfect square in disguise, in which case you can cancel out the square root and have a much simpler problem.

    • 2

      Perform any u-substitution in both the numerator and denominator to simplify. Remember that rearranging a substitution can sometimes enable you to use a variation of it. For example, u = x - 2 can be rearranged to x = u + 2, if you need to substitute a lone "x." Don't forget that sometimes you may need to make multiple substitutions, first using a u-substitution and then a v-substitution, until the integral is simple enough.

    • 3

      Perform any trig substitutions you see. Most of these problems involve a trig substitution, so remember to also keep an eye out for identities like tan^2(theta) + 1 = sec^2(theta).

    • 4

      Integrate, using power rules, integration by parts or integral tables. Undo any substitutions you made until everything is back in terms of "x." For indefinite integrals, don't forget to write "+ c" at the end, and for definite integrals, evaluate the solution for the limits given.

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