{VERSION 3 0 "IBM INTEL NT" "3.0" } {USTYLETAB {CSTYLE "Maple Input" -1 0 "Courier" 0 1 255 0 0 1 0 1 0 0 1 0 0 0 0 }{CSTYLE "2D Math" -1 2 "Times" 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 }{CSTYLE "2D Comment" 2 18 "" 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 } {CSTYLE "" -1 256 "" 1 18 0 0 0 0 0 1 0 0 0 0 0 0 0 }{CSTYLE "" -1 257 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 258 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 259 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 260 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 261 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 262 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 263 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 264 "" 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 }{CSTYLE "" -1 265 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 266 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 267 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 268 "" 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 }{CSTYLE "" -1 269 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 270 "" 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 }{CSTYLE "" -1 271 "" 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 }{CSTYLE "" -1 272 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 }{CSTYLE "" -1 273 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 }{CSTYLE "" -1 274 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 }{PSTYLE "Normal" -1 0 1 {CSTYLE "" -1 -1 "Times" 1 14 0 0 0 0 2 2 2 0 0 0 0 0 0 }0 0 0 -1 -1 -1 0 0 0 0 0 0 -1 0 } {PSTYLE "Heading 1" 0 3 1 {CSTYLE "" -1 -1 "" 1 18 0 0 0 0 0 1 0 0 0 0 0 0 0 }1 0 0 0 6 6 0 0 0 0 0 0 -1 0 }{PSTYLE "Title" 0 18 1 {CSTYLE "" -1 -1 "" 1 18 0 0 0 0 0 1 1 0 0 0 0 0 0 }3 0 0 -1 12 12 0 0 0 0 0 0 19 0 }{PSTYLE "R3 Font 0" -1 256 1 {CSTYLE "" -1 -1 "Helvetica" 1 14 0 0 0 0 2 1 2 0 0 0 0 0 0 }0 0 0 -1 -1 -1 0 0 0 0 0 0 -1 0 } {PSTYLE "R3 Font 2" -1 257 1 {CSTYLE "" -1 -1 "Courier" 1 14 0 0 0 0 2 2 2 0 0 0 0 0 0 }0 0 0 -1 -1 -1 0 0 0 0 0 0 -1 0 }{PSTYLE "" 0 258 1 {CSTYLE "" -1 -1 "" 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 }3 0 0 -1 -1 -1 0 0 0 0 0 0 -1 0 }{PSTYLE "" 0 259 1 {CSTYLE "" -1 -1 "" 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 }3 0 0 -1 -1 -1 0 0 0 0 0 0 -1 0 }} {SECT 0 {SECT 0 {PARA 3 "" 0 "" {TEXT -1 26 "Chapter Improper Integral s" }}{EXCHG {PARA 18 "" 0 "" {TEXT -1 0 "" }}{PARA 0 "" 0 "" {TEXT -1 190 "Up to now all of the functions that have been studied with regard to integration have been bounded and defined on intervals of finite l ength. In this section you will learn how to deal with" }}{PARA 0 "" 0 "" {TEXT -1 29 "integrals like the following:" }}{PARA 0 "" 0 "" {TEXT -1 17 "1. The integral " }{XPPEDIT 18 0 "int(exp(-x^2),x=0..inf inity) " "6#-%$intG6$-%$expG6#,$*$%\"xG\"\"#!\"\"/F+;\"\"!%)infinityG " }{TEXT -1 1 "." }}{PARA 0 "" 0 "" {TEXT -1 17 "2. The integral " } {XPPEDIT 18 0 "int(1/(sqrt(x*(1-x))),x=0..1)" "6#-%$intG6$*&\"\"\"\"\" \"-%%sqrtG6#*&%\"xGF(,&\"\"\"F(F-!\"\"F(F0/F-;\"\"!\"\"\"" }}{PARA 0 " " 0 "" {TEXT -1 39 "Integrals like the last two are called " }{TEXT 256 18 "improper integrals" }{TEXT -1 1 "." }}{PARA 0 "" 0 "" {TEXT -1 62 "For example, consider the problem of integrating the function \+ " }{XPPEDIT 18 0 "exp(-x^2)" "6#-%$expG6#,$*$%\"xG\"\"#!\"\"" }{TEXT -1 42 " over variousfinite intervals of the form " }{TEXT 258 5 "[0,T] " }{TEXT -1 11 ", where " }{TEXT 257 5 "T > 0" }{TEXT -1 1 "." }}}} {SECT 0 {PARA 3 "" 0 "" {TEXT -1 15 "Maple Try these" }}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "evalf(int(exp(-x^2),x=0..2));" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "evalf(int(exp(-x^2),x=0..4));" }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "evalf(int(exp(-x^2),x=0..5)) ;" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "evalf(int(exp(-x^2),x= 0..6));" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "evalf(int(exp(-x ^2),x=0..7));" }}}}{SECT 0 {PARA 3 "" 0 "" {TEXT -1 12 "Introduction" }}{EXCHG {PARA 0 "" 0 "" {TEXT -1 47 "Observe, that the values of the integral for " }{TEXT 259 5 "T = 5" }{TEXT -1 9 " through " }{TEXT 260 5 "T = 7" }{TEXT -1 18 " are unchanged to " }{TEXT 261 2 "10" } {TEXT -1 36 " digits of accuracy. We know that " }{XPPEDIT 18 0 "0" }}{PARA 0 "" 0 "" {TEXT -1 7 "and \+ so " }}{PARA 259 "" 0 "" {TEXT -1 0 "" }}{PARA 0 "" 0 "" {XPPEDIT 18 0 "int( exp(-x^2),x=0..5) < int( exp(-x^2),x=0..7)" "6#2-%$intG6$-%$ expG6#,$*$%\"xG\"\"#!\"\"/F,;\"\"!\"\"&-F%6$-F(6#,$*$F,\"\"#F./F,;F1\" \"(" }{TEXT -1 2 ". " }}{PARA 0 "" 0 "" {TEXT -1 67 "Looking at the si tuation from a geometric point of view we now plot" }}{PARA 0 "" 0 "" {TEXT -1 62 "the indefinite integral of exp(-x^2) over the interval [ 0,7]." }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 35 "plot(int(exp(-t^2),t=0..x) ,x=0..7);" }}}}{SECT 0 {PARA 3 "" 0 "" {TEXT -1 9 "Exmaple 1" }} {EXCHG {PARA 0 "" 0 "" {TEXT -1 48 "According to the graph of the ant iderivative, " }{TEXT 265 4 "F(x)" }{TEXT -1 6 ", of " }{XPPEDIT 18 0 "exp(-x^2)" "6#-%$expG6#,$*$%\"xG\"\"#!\"\"" }{TEXT -1 5 " it " }} {PARA 0 "" 0 "" {TEXT -1 13 "appears that " }{TEXT 266 4 "F(x)" } {TEXT -1 26 " has horizontal asymptote." }}{PARA 0 "" 0 "" {TEXT 264 9 "Example 1" }{TEXT -1 32 " Determine that the integral of " } {XPPEDIT 18 0 "1/(t^2* ln(t))" "6#*&\"\"\"\"\"\"*&%\"tG\"\"#-%#lnG6#F' F%!\"\"" }{TEXT -1 20 " over the half-line " }{XPPEDIT 18 0 "[2,infini ty)" "6#7$\"\"#%)infinityG" }}{PARA 0 "" 0 "" {TEXT -1 30 "converges. \+ Find the limit to " }{TEXT 267 2 "10" }{TEXT -1 20 " digits of accura cy." }}{PARA 0 "" 0 "" {TEXT 268 9 "Solution:" }{TEXT -1 79 " To prov e the improper integral converges, we have the following two methods: \+ " }}{PARA 0 "" 0 "" {TEXT 273 8 "Method 1" }{TEXT -1 27 ". (Comparison Test) Since " }{TEXT 272 2 "ln" }{TEXT -1 26 " is increasing we ha ve " }}{PARA 0 "" 0 "" {XPPEDIT 18 0 "ln(t)>=ln(2) " "6#1-%#lnG6#\"\" #-F%6#%\"tG" }{TEXT -1 6 " for " }{XPPEDIT 18 0 "t >= 2" "6#1\"\"#% \"tG" }{TEXT -1 18 ". This means that " }{XPPEDIT 18 0 "1/(t^2*ln(t)) \+ <=1/(ln(2)*t^2)" "6#1*&\"\"\"\"\"\"*&%\"tG\"\"#-%#lnG6#F(F&!\"\"*&\"\" \"F&*&-F+6#\"\"#F&*$F(\"\"#F&F-" }}{PARA 0 "" 0 "" {TEXT -1 8 "for all " }{XPPEDIT 18 0 "t >= 2" "6#1\"\"#%\"tG" }{TEXT -1 5 ". So " } {XPPEDIT 18 0 "int(1/(t^2*ln(t)),t = 2 .. infinity);" "6#-%$intG6$*&\" \"\"\"\"\"*&%\"tG\"\"#-%#lnG6#F*F(!\"\"/F*;\"\"#%)infinityG" }{TEXT -1 23 " is convergent because " }{XPPEDIT 18 0 "int(1/(t^2*ln(2)),t = \+ 2 .. infinity);" "6#-%$intG6$*&\"\"\"\"\"\"*&%\"tG\"\"#-%#lnG6#\"\"#F( !\"\"/F*;\"\"#%)infinityG" }{TEXT -1 4 " is." }}{PARA 0 "" 0 "" {TEXT 274 9 "Method 2." }{TEXT -1 105 " (If the antiderivative function is i ncreasing and bounded above, then the antiderivative is convergent.)" }}{PARA 0 "" 0 "" {TEXT -1 0 "" }}{PARA 0 "" 0 "" {TEXT -1 14 "Let F (x) be " }{XPPEDIT 18 0 "int(1/(t^2*ln(t)),t = 2 .. x);" "6#-%$intG6$* &\"\"\"\"\"\"*&%\"tG\"\"#-%#lnG6#F*F(!\"\"/F*;\"\"#%\"xG" }{TEXT -1 10 ". Since " }{TEXT 269 2 "ln" }{TEXT -1 26 " is increasing we ha ve " }}{PARA 0 "" 0 "" {XPPEDIT 18 0 "ln(t)>=ln(2) " "6#1-%#lnG6#\"\" #-F%6#%\"tG" }{TEXT -1 6 " for " }{XPPEDIT 18 0 "t >= 2" "6#1\"\"#% \"tG" }{TEXT -1 18 ". This means that " }{XPPEDIT 18 0 "1/(t^2*ln(t)) \+ <=1/(ln(2)*t^2)" "6#1*&\"\"\"\"\"\"*&%\"tG\"\"#-%#lnG6#F(F&!\"\"*&\"\" \"F&*&-F+6#\"\"#F&*$F(\"\"#F&F-" }}{PARA 0 "" 0 "" {TEXT -1 8 "for all " }{XPPEDIT 18 0 "t >= 2" "6#1\"\"#%\"tG" }{TEXT -1 2 ". " }}{PARA 0 "" 0 "" {TEXT -1 16 "It follows that " }}{PARA 0 "" 0 "" {TEXT -1 0 " " }}{PARA 0 "" 0 "" {TEXT -1 6 "F(x) =" }{XPPEDIT 18 0 " int(1/(t^2*ln (t)),t = 2 .. x) <= int(1/(t^2*ln(2)),t=2..x)" "6#1-%$intG6$*&\"\"\" \"\"\"*&%\"tG\"\"#-%#lnG6#F+F)!\"\"/F+;\"\"#%\"xG-F%6$*&\"\"\"F)*&F+\" \"#-F.6#\"\"#F)F0/F+;\"\"#F4" }{TEXT -1 4 " = " }{XPPEDIT 18 0 "(1/2 \+ - 1/x)/ln(2)<=1/(2*ln(2))" "6#1*&,&*&\"\"\"\"\"\"\"\"#!\"\"F(*&\"\"\"F (%\"xGF*F*F(-%#lnG6#\"\"#F**&\"\"\"F(*&\"\"#F(-F/6#\"\"#F(F*" }{TEXT -1 11 ", for all " }{XPPEDIT 18 0 "x >= 2" "6#1\"\"#%\"xG" }{TEXT -1 2 ". " }}{PARA 0 "" 0 "" {TEXT -1 0 "" }}{PARA 0 "" 0 "" {TEXT -1 15 "Since F'(x) = " }{XPPEDIT 18 0 "1/(x^2*ln x)" "6#*&\"\"\"\"\"\"*( %\"xG\"\"#%#lnGF%F'F%!\"\"" }{TEXT -1 183 " > 0 for x >2, F(x) is an increasing function which is bounded above by 1/(2*ln(2)). Thus \+ the integral converges. Its value to 10 digits of accuracy is given b y the following." }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 39 "I1 := Int(1/(x^ 2*ln(x)),x=2..infinity);" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 16 "I1 := evalf(I1);" }}}}{SECT 0 {PARA 3 "" 0 "" {TEXT -1 9 "Example 2" }}{EXCHG {PARA 0 "" 0 "" {TEXT 270 11 "Example 2. " }{TEXT -1 31 " De termine that the integral " }{XPPEDIT 18 0 "int(1/(t^2+sqrt(t)),t = 0 .. 1);" "6#-%$intG6$*&\"\"\"\"\"\",&*$%\"tG\"\"#F(-%%sqrtG6#F+F(!\"\" /F+;\"\"!\"\"\"" }{TEXT -1 21 " converges. Find the" }}{PARA 0 "" 0 " " {TEXT -1 31 "limit to 10 digits of accuracy." }}{PARA 0 "" 0 "" {TEXT 271 8 "Solution" }{TEXT -1 7 ": Let " }}{PARA 0 "" 0 "" {TEXT -1 18 " " }{XPPEDIT 18 0 "F(x) = int(1/(t^2+sqrt(t)), t=x..1)" "6#/-%\"FG6#%\"xG-%$intG6$*&\"\"\"\"\"\",&*$%\"tG\"\"#F--%%sq rtG6#F0F-!\"\"/F0;F'\"\"\"" }{TEXT -1 2 ". " }}{PARA 0 "" 0 "" {TEXT -1 53 "Since t^2 > 0 for all t not equal to 0, we have " }}{PARA 0 "" 0 "" {TEXT -1 17 " " }{XPPEDIT 18 0 "1/(t^2+ sqrt (t)) < 1/sqrt(t))" "6#2*&\"\"\"\"\"\",&*$%\"tG\"\"#F&-%%sqrtG6#F)F&!\" \"*&\"\"\"F&-F,6#F)F." }{TEXT -1 1 "." }}{PARA 0 "" 0 "" {TEXT -1 11 " This means " }{XPPEDIT 18 0 "int(1/(t^2+ sqrt(t)),t=x..1) <= int(1/sq rt(t),t=x..1) " "6#1-%$intG6$*&\"\"\"\"\"\",&*$%\"tG\"\"#F)-%%sqrtG6#F ,F)!\"\"/F,;%\"xG\"\"\"-F%6$*&\"\"\"F)-F/6#F,F1/F,;F4\"\"\"" }{TEXT -1 3 " = " }{XPPEDIT 18 0 "2 - 2 sqrt(x) <= 2" "6#1,&\"\"#\"\"\"*&\"\" #F&-%%sqrtG6#%\"xGF&!\"\"\"\"#" }{TEXT -1 1 "," }}{PARA 0 "" 0 "" {TEXT -1 2 " " }}{PARA 0 "" 0 "" {TEXT -1 161 "for all 0 < x <1. Not ice that F'(x) >0 for all 0 " 0 "" {MPLTEXT 1 0 34 "I2 := Int(1/(x^2+sqrt(x)),x=0..1);" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 16 "I2 := evalf(I2);" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "plot(1/(x^2+sqrt(x)),x=0..1);" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}}}{MARK "0" 0 }{VIEWOPTS 1 1 0 1 1 1803 }