Cambridge Additional Mathematics

(singke) #1
cis an arbitrary constant called
the or
.

constant of integration
integrating constant

Integration (Chapter 15) 425

These rules or combinations of them can be used to differentiate all of the functions we consider in this
course. Given an algebraic formula, we can repeatedly apply these rules until we get to basic functions such
asxnorsinx, which we know how to differentiate.
However, the task of findingantiderivativesis not so easy. Given an algebraic formula there is no simple
list of rules to find the antiderivative.

The problem was finally solved in 1968 by Robert Henry Risch. He devised a method for deciding if a
function has an elementary antiderivative, and if it does, finding it. The original summary of his method
took over 100 pages. Later developments from this are now used in all computer algebra systems.

Fortunately, our course is restricted to a few special cases.

RULES FOR INTEGRATION


Forka constant,
d
dx
(kx+c)=k )

Z
kdx=kx+c

If n 6 =¡ 1 ,
d
dx

μ
xn+1
n+1
+c


=
(n+1)xn
n+1
=xn )

Z
xndx=

xn+1
n+1

+c, n 6 =¡ 1

d
dx
(ex+c)=ex )

Z
exdx=ex+c

d
dx
(sinx+c) = cosx )

Z
cosxdx= sinx+c

d
dx
(¡cosx+c) = sinx )

Z
sinxdx=¡cosx+c

Function Integral

k, a constant kx+c

xn, n 6 =¡ 1
xn+1
n+1

+c

ex ex+c

cosx sinx+c

sinx ¡cosx+c

Remember that you can always check your integration by differentiating the resulting function.

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