antidifferentiation by substitution if y = f(x) we can denote the derivative of f by either dy/dx or...
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Antidifferentiation by Substitution• If y = f(x) we can denote the derivative of f by either
dy/dx or f’(x). What can we use to denote the antiderivative of f?– We have seen that the general solution to the
differential equation dy/dx = f(x) actually consists of an infinite family of functions of the form F(x) + C, where F’(x) = f(x).• Both the name for this family of functions and the symbol we
use to denote it are closely related to the definite integral because of the Fundamental Theorem of Calculus.
• The symbol is an integral sign, the function f is the integrand of the integral, and x is the variable of
integration.
Evaluating an Indefinite Integral• Evaluate 2( sin ) .x x dx
2( sin )x x dx3
cos3
xx C
Paying Attention to the Differential• Let f(x) = x³ + 1 and let u = x². Find each of the
following antiderivatives in terms of x:a.) b.) c.)( )f x dx ( )f u du ( )f u dx.) ( )a f x dx 3( 1)x dx
4
4
xx C
.) ( )b f u du 3( 1)u du 4
4
uu C
2 42( )
4
xx C
82
4
xx C
Paying Attention to the Differential• Let f(x) = x³ + 1 and let u = x². Find each of the
following antiderivatives in terms of x:a.) b.) c.)( )f x dx ( )f u du ( )f u dx
( )f u dx 3( 1)u dx 2 3(( ) 1)x dx 6( 1)x dx
7
7
xx C
Using Substitution• Evaluate
• Let u = cos xdu/dx = -sin xdu = - sin x dx
Using Substitution• Evaluate• Let u = 5 + 2x³, du = 6x² dx.
Using Substitution• Evaluate• We do not recall a function whose derivative is
cot 7x, but a basic trigonometric identity changes the integrand into a form that invites the substitution u = sin 7x, du = 7 cos 7x dx.
Setting Up a Substitution with a Trigonometric Identity• Find the indefinite integrals. In each case you can
use a trigonometric identity to set up a substitution.
Setting Up a Substitution with a Trigonometric Identity• Find the indefinite integrals. In each case you can
use a trigonometric identity to set up a substitution.
Setting Up a Substitution with a Trigonometric Identity• Find the indefinite integrals. In each case you can
use a trigonometric identity to set up a substitution.
Evaluating a Definite Integral by Substitution• Evaluate
• Let u = tan x and du = sec²x dx.
That Absolute Value Again• Evaluate