Things You Need to Know
for Differential Equations, an episodic review of useful facts
from calculus.
Aug. 29:
( f '(x)
/ f(x) ) dx = ln|f(x)| + C
- (d/dx)(tan-1(x)) = 1/(1+x2)
so
1/(1+x2)
dx = tan-1(x) + C
Aug. 31:
- ea+b = eaeb
- eab = (ea )b
- ln(a/b) = ln(a)-ln(b)
- ln(ab) = ln(a)+ln(b)
- ln(ar ) = r ln(a)
- eln(x) = x and ln(ex) = x for all real values of x for which both sides are defined
- ln(a+b) usually doesn't break up
- ea+b = ea + eb Wrong!
Sept. 5:
- Integration by parts:
udv = uv -
vdu; pick u so that du is easier to deal with and v isn't much worse than dv.
Last Modified Aug.. 31, 2012.
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