Why subsitution method for integration always work ?

Click For Summary
SUMMARY

The substitution method for integration is effective due to the application of the chain rule and the implicit function theorem. When substituting variables, the relationship between differentials, such as dx and du, is maintained through the equation dg = g'(x)dx. This allows for the transformation of integrals into a more manageable form, as demonstrated by the relationship f(g(x))g'(x)dx = f(g)dg. The method relies on the fundamental principles of calculus, ensuring that the substitution is valid regardless of the specific form of the integral.

PREREQUISITES
  • Understanding of the chain rule in calculus
  • Familiarity with the implicit function theorem
  • Knowledge of differential notation and transformations
  • Basic proficiency in integral calculus
NEXT STEPS
  • Study the chain rule in more depth, focusing on its applications in integration
  • Explore the implicit function theorem and its implications for calculus
  • Practice solving integrals using substitution with various functions
  • Review differential notation and its role in calculus transformations
USEFUL FOR

Students of calculus, mathematics educators, and anyone looking to deepen their understanding of integration techniques and the underlying principles of substitution methods.

MIB
Messages
17
Reaction score
0
why substitution method for integration always work ?

Why can we completely treat dx and du known in substitution method completely like differentials even if we don't have ∫f(g(x))g'(x) dx , i.e : why we can substitute x in terms of u and dx in terms of du .

thanks
 
Last edited:
Physics news on Phys.org
The chain rule and implicit function theorem
if g is chosen as a function of x we have
f(g(x))g'(x) dx=f(g)dg
which comes from
dg=g'(x)dx
which is the chain rule precisely
if instead we chose an implicit relationship between g and x we have
h(g,x)=0
dh=hxdx+hgdg=0
dg=[dg/dx]dx=[-hx/hg]dx
which is the chain rule precisely
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 22 ·
Replies
22
Views
4K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 21 ·
Replies
21
Views
4K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 19 ·
Replies
19
Views
5K
  • · Replies 6 ·
Replies
6
Views
3K