Q. Evaluate the integral and express your answer in simplest form.∫9+25x2−2dxAnswer:
Recognize Integral Form: We are given the integral to evaluate: ∫9+25x2−2dxFirst, we notice that the denominator can be written as a sum of squares, which suggests a trigonometric substitution. However, we can also use a direct substitution if we recognize that the integral is in the form of an arctangent function. We will use the substitution method.
Substitution with u: Let's make the substitution u=5x, which means du=5dx. We need to express dx in terms of du, so we get dx=5du.
Factor Out Constants: Now we substitute 5x with u and dx with du/5 in the integral:∫9+25x2−2dx=∫9+u2−2⋅(5du)We can factor out constants from the integral:=(−52)⋅∫9+u21du
Use Integral Formula: The integral of a2+u21 is a1⋅arctan(au)+C, where a is a constant. In our case, a2=9, so a=3. We can now integrate using this formula:(−52)⋅∫9+u21du=(−52)⋅(31)⋅arctan(3u)+C
Simplify Constant Factors: Simplify the constant factors:(−52)×(31)=−152So the integral becomes:−152×arctan(3u)+C
Substitute Back u: Now we substitute back u=5x to get the integral in terms of x:−152⋅arctan(35x)+C
Final Indefinite Integral: We have found the indefinite integral in its simplest form: ∫9+25x2−2dx=15−2⋅arctan(35x)+C
More problems from Find indefinite integrals using the substitution