An antiderivative of a function f is a function whose derivative is
f.  In other words, F is an antiderivative of f if F' = f. To find
an antiderivative for a function f, we can often reverse the process of
differentiation.
For example, if f = x4, then an antiderivative of f is
F =  x5, which can be found by reversing the power rule.
Notice that not only is
x5, which can be found by reversing the power rule.
Notice that not only is  x5 an antiderivative of f, but
so are
x5 an antiderivative of f, but
so are  x5 + 4,
x5 + 4,  x5 + 6, etc.  In fact, adding or
subtracting any constant would be acceptable.
x5 + 6, etc.  In fact, adding or
subtracting any constant would be acceptable.
This should make sense algebraically, since the process of taking the
derivative (i.e.  going from F to f) eliminates the constant term of
F.
Because a single continuous function has
infinitely many antiderivatives, we do not refer to "the antiderivative",
but rather, a "family" of antiderivatives, each of which differs by a
constant.  So, if F is an antiderivative of f, then G = F + c is also
an antiderivative of f, and F and G are in the same family of
antiderivatives.
 
Indefinite Integral
The notation used to refer to antiderivatives is the indefinite integral.  f (x)dx  means the antiderivative of f
with respect to x.  If F is an antiderivative of f, we can write
f (x)dx  means the antiderivative of f
with respect to x.  If F is an antiderivative of f, we can write  f (x)dx = F + c.  In this context, c is 
called the constant of integration.
f (x)dx = F + c.  In this context, c is 
called the constant of integration.
To find antiderivatives of basic functions, the following rules can be used:
- 
 xndx = xndx = xn+1 + c as long as n does not equal -1.
This is essentially the power rule for derivatives in reverse xn+1 + c as long as n does not equal -1.
This is essentially the power rule for derivatives in reverse
- 
 cf (x)dx = c cf (x)dx = c f (x)dx.
That is, a scalar can be pulled out of the integral. f (x)dx.
That is, a scalar can be pulled out of the integral.
- 
 (f (x) + g(x))dx = (f (x) + g(x))dx = f (x)dx + f (x)dx + g(x)dx.
The antiderivative of a sum is the sum of the antiderivatives. g(x)dx.
The antiderivative of a sum is the sum of the antiderivatives.
- 
 sin(x)dx = - cos(x) + c sin(x)dx = - cos(x) + c
  cos(x)dx = sin(x) + c cos(x)dx = sin(x) + c
  sec2(x)dx = tan(x) + c sec2(x)dx = tan(x) + c
 These are the opposite of the trigonometric derivatives.