Integration techniques
Weeks 1-2You can pick substitution, parts, partial fractions or a trig method for a hard integral. You can also check your answer by differentiating it back.
- Choose u so that du already appears in the integral.
- Use integration by parts on x times e to the x.
- Split a fraction into partial fractions before integrating.
Worked example
Integrate 2x(x squared + 1) cubed dx
- Let u = x squared + 1, so du = 2x dx
- The integral becomes u cubed du, which is u to the fourth over 4
Answer(x squared + 1) to the fourth, divided by 4, plus C
Most common mistakeChanging the variable but not the differential: writing the integral of u cubed dx leaves a stray 2x that never gets accounted for.