indefinite integrals, applications
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Indefinite Integrals, ApplicationsSection 6.1b
The set of all antiderivatives of a function isthe indefinite integral of with respect to and isdenoted by
f x dxIntegral Sign
IntegrandVariable ofIntegration
Also, recall that a function is an antiderivativeof if F x f x
Definition: Indefinite Integral f x
f x
F x f x
Definition: Indefinite IntegralThen all antiderivatives of a function vary by constants:
f x dx F x C What keeps this integral from being “definite”???
The constant C is the constant of integration andis an arbitrary constant.
When we find we have integrated or evaluated the integral…
F x C f
Integral FormulasIndefinite Integral
1
1
nn xx dx C
n
Reversed Derivative Formula
1. (a)
1n
1
1
nnd x x
dx n
1n
lndx x Cx
(b) 1lnd xdx x
kxkx ee dx C
k 2.
kxkxd e e
dx k
Integral FormulasIndefinite Integral Reversed Derivative Formula
cossin kxkx dx Ck
3.cos sind kx kx
dx k
sincos kxkx dx Ck
4.sin cosd kx kx
dx k
2sec tanx dx x C 5. 2tan secd x xdx
Integral FormulasIndefinite Integral Reversed Derivative Formula
2csc cotx dx x C 6. 2cot cscd x xdx
sec tan secx x dx x C 7. sec sec tand x x xdx
csc cot cscx x dx x C 8.
csc csc cotd x x xdx
Using Integral FormulasEvaluate:
5x dx6
6x C
1 dxx 1 2x dx 1 22x C 2 x C
3xe dx3
3
xe C
313
xe C
cos2x dx
sin 1 21 2
xC 2sin
2x C
Properties of Indefinite Integrals
kf x dx k f x dx Let k be a real number.
1. Constant Multiple Rule:
f x dx f x dx If k = –1, then:
f x g x dx f x dx g x dx 2. Sum and Difference Rule:
Integrating Term by Term 2 2 5x x dx Evaluate
2 2 5x dx xdx dx 3
21 2 35
3x C x C x C
But we can simply combine all of these constants!!!
3
2 22 5 53xx x dx x x C
Do Now – p.314, #55How long did it take the hammer and feather to fall 4 ft on themoon? Solve the following initial value problem for s as afunction of t. Then find the value of t that makes s equal to 0.
Differential equation:
22
2 5.2ft secd sdt
Initial conditions: and when0dsdt
4s 0t 2
2 5.2d s dt dtdt
15.2ds t C
dt
10 5.2 0 C 1 0C
Velocity: 5.2ds tdt
Do Now – p.314, #55How long did it take the hammer and feather to fall 4 ft on themoon? Solve the following initial value problem for s as afunction of t. Then find the value of t that makes s equal to 0.
Differential equation:
22
2 5.2ft secd sdt
Initial conditions: and when0dsdt
4s 0t
5.2ds dt tdtdt
2
22.6s t C
2 24 2.6 0 C 2 4C
Position: 22.6 4s t t
Do Now – p.314, #55How long did it take the hammer and feather to fall 4 ft on themoon? Solve the following initial value problem for s as afunction of t. Then find the value of t that makes s equal to 0.
Differential equation:
22
2 5.2ft secd sdt
Initial conditions: and when0dsdt
4s 0t
22.6 4s t t Solving , we have 0s t 2 42.6
t
Take the positive solution… 1.240t They took about 1.240 seconds to fall
More Application ProblemsA right circular cylindrical tank with radius 5 ft and height 16 ftthat was initially full of water is being drained at the rate of0.5 x ft /min (x = water’s depth). Find a formula for the depthand the amount of water in the tank at any time t. How long willit take the tank to empty?
3
x
2V r h 25V x 25 x
Diff Eq: 25dV dxdt dt
0.5 25 dxxdt
More Application ProblemsA right circular cylindrical tank with radius 5 ft and height 16 ftthat was initially full of water is being drained at the rate of0.5 x ft /min (x = water’s depth). Find a formula for the depthand the amount of water in the tank at any time t. How long willit take the tank to empty?
3
50dx xdt
Initial Condition:
0 16x
1 2 150
dxxdt
Solve Analytically:
1 2 150
dxx dt dtdt
1 2 1
50x dx dt
Diff Eq: 0.5 25 dxxdt
More Application ProblemsA right circular cylindrical tank with radius 5 ft and height 16 ftthat was initially full of water is being drained at the rate of0.5 x ft /min (x = water’s depth). Find a formula for the depthand the amount of water in the tank at any time t. How long willit take the tank to empty?
3
1 2 12 16 050
C
Solve Analytically:
8C
1 2 1250
x t C
1 2 150
x dx dt
Initial Condition:
1 2 12 850
x t
2
4100tx
More Application ProblemsA right circular cylindrical tank with radius 5 ft and height 16 ftthat was initially full of water is being drained at the rate of0.5 x ft /min (x = water’s depth). Find a formula for the depthand the amount of water in the tank at any time t. How long willit take the tank to empty?
3
400t
Equation for volume: 2
25 25 4100tV x
At what t is V = 0? minutes
(The tank will be empty in about 21 hours)
More Application ProblemsYou are driving along a highway at a steady 60 mph (88 ft/sec)when you see an accident ahead and slam on the brakes. Whatconstant deceleration is required to stop your car in 242 feet?First, solve the following initial value problem:
2
2
d s kdt
Differential Equation: (k constant)
88dsdt
Initial Conditions: 0s and 0t when
88ds ktdt
Velocity:
2
882kts t Solution:
More Application ProblemsYou are driving along a highway at a steady 60 mph (88 ft/sec)when you see an accident ahead and slam on the brakes. Whatconstant deceleration is required to stop your car in 242 feet?
Next, find the value of t that makes ds/dt = 0:
88ds ktdt
Velocity:
2
882kts t Solution:
88 0kt 88tk
More Application ProblemsYou are driving along a highway at a steady 60 mph (88 ft/sec)when you see an accident ahead and slam on the brakes. Whatconstant deceleration is required to stop your car in 242 feet?
88ds ktdt
Velocity:
2
882kts t Solution:
Finally, find the value of k that makes s = 242 for the previouslyfound value of t :
88 242sk
288 8888 2422kk k
3872 242k
216ft seck
You would need to decelerate at thisconstant rate in order to stop in 242 feet!!!
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