When integrating, what are all the exact requirements for a substitution to be valid?











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There are many examples on this site of substitutions that are not valid for varying reasons. But there are probably many more that I still don't know of.



When working with definite and indefinite integrals, what are all the rules for valid substitutions?



(It would also be nice to have explanations but this is not necessary.)










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  • I think all monotone derivable functions $f$ which derivate doesn't vanish.
    – P De Donato
    Nov 21 at 12:18










  • It's best to remember the rule of substitution. There are some variations of the rule and hence it may be described differently in various textbooks. Follow the one prescribed in your textbook. Apostol gives it as: $int_{g(a)} ^{g(b)} f(x) , dx=int_{a}^{b} f(g(t)) g'(t) , dt$ if $g'$ is continuous on $[a, b] $ and $f$ is continuous on $g([a, b]) $.
    – Paramanand Singh
    Nov 21 at 14:36















up vote
1
down vote

favorite












There are many examples on this site of substitutions that are not valid for varying reasons. But there are probably many more that I still don't know of.



When working with definite and indefinite integrals, what are all the rules for valid substitutions?



(It would also be nice to have explanations but this is not necessary.)










share|cite|improve this question






















  • I think all monotone derivable functions $f$ which derivate doesn't vanish.
    – P De Donato
    Nov 21 at 12:18










  • It's best to remember the rule of substitution. There are some variations of the rule and hence it may be described differently in various textbooks. Follow the one prescribed in your textbook. Apostol gives it as: $int_{g(a)} ^{g(b)} f(x) , dx=int_{a}^{b} f(g(t)) g'(t) , dt$ if $g'$ is continuous on $[a, b] $ and $f$ is continuous on $g([a, b]) $.
    – Paramanand Singh
    Nov 21 at 14:36













up vote
1
down vote

favorite









up vote
1
down vote

favorite











There are many examples on this site of substitutions that are not valid for varying reasons. But there are probably many more that I still don't know of.



When working with definite and indefinite integrals, what are all the rules for valid substitutions?



(It would also be nice to have explanations but this is not necessary.)










share|cite|improve this question













There are many examples on this site of substitutions that are not valid for varying reasons. But there are probably many more that I still don't know of.



When working with definite and indefinite integrals, what are all the rules for valid substitutions?



(It would also be nice to have explanations but this is not necessary.)







calculus integration






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 21 at 11:56









PKBeam

3129




3129












  • I think all monotone derivable functions $f$ which derivate doesn't vanish.
    – P De Donato
    Nov 21 at 12:18










  • It's best to remember the rule of substitution. There are some variations of the rule and hence it may be described differently in various textbooks. Follow the one prescribed in your textbook. Apostol gives it as: $int_{g(a)} ^{g(b)} f(x) , dx=int_{a}^{b} f(g(t)) g'(t) , dt$ if $g'$ is continuous on $[a, b] $ and $f$ is continuous on $g([a, b]) $.
    – Paramanand Singh
    Nov 21 at 14:36


















  • I think all monotone derivable functions $f$ which derivate doesn't vanish.
    – P De Donato
    Nov 21 at 12:18










  • It's best to remember the rule of substitution. There are some variations of the rule and hence it may be described differently in various textbooks. Follow the one prescribed in your textbook. Apostol gives it as: $int_{g(a)} ^{g(b)} f(x) , dx=int_{a}^{b} f(g(t)) g'(t) , dt$ if $g'$ is continuous on $[a, b] $ and $f$ is continuous on $g([a, b]) $.
    – Paramanand Singh
    Nov 21 at 14:36
















I think all monotone derivable functions $f$ which derivate doesn't vanish.
– P De Donato
Nov 21 at 12:18




I think all monotone derivable functions $f$ which derivate doesn't vanish.
– P De Donato
Nov 21 at 12:18












It's best to remember the rule of substitution. There are some variations of the rule and hence it may be described differently in various textbooks. Follow the one prescribed in your textbook. Apostol gives it as: $int_{g(a)} ^{g(b)} f(x) , dx=int_{a}^{b} f(g(t)) g'(t) , dt$ if $g'$ is continuous on $[a, b] $ and $f$ is continuous on $g([a, b]) $.
– Paramanand Singh
Nov 21 at 14:36




It's best to remember the rule of substitution. There are some variations of the rule and hence it may be described differently in various textbooks. Follow the one prescribed in your textbook. Apostol gives it as: $int_{g(a)} ^{g(b)} f(x) , dx=int_{a}^{b} f(g(t)) g'(t) , dt$ if $g'$ is continuous on $[a, b] $ and $f$ is continuous on $g([a, b]) $.
– Paramanand Singh
Nov 21 at 14:36















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