Page 33 - Calculus for the Clueless
P. 33
Example 17—
Sometimes you use a trig substitution even though there is no square root; x = 3 tan u. dx = 3
2
sec u du.
One last example, but be warned! A trig substitution may work, but another method may be a lot easier.
Example 18—
2
x = 3 tan u will work. But you may not finish for two years. The best? u = x + 9; du = 2x dx.
