Another Trigonometric Integral Problem Help Me

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SUMMARY

The integral ∫sec²(x) * tan(x) dx can be solved using the substitution method with u = tan(x), leading to du = sec²(x) dx. The integral simplifies to ∫(1 + u²)u du, which results in (1/2)tan²(x) + (1/3)tan³(x) + C. However, the correct answer is (1/2)tan²(x) + C, indicating that the additional term (1/3)tan³(x) is unnecessary for this specific integral.

PREREQUISITES
  • Understanding of integral calculus
  • Familiarity with trigonometric identities, specifically sec²(x) = 1 + tan²(x)
  • Knowledge of substitution methods in integration
  • Ability to manipulate algebraic expressions involving trigonometric functions
NEXT STEPS
  • Review the method of integration by substitution in calculus
  • Study trigonometric identities and their applications in integration
  • Practice solving integrals involving secant and tangent functions
  • Explore advanced integration techniques, such as integration by parts
USEFUL FOR

Students studying calculus, particularly those focusing on integration techniques, and educators seeking to clarify common mistakes in solving trigonometric integrals.

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Homework Statement


∫sec^2 (x) * tan (x) dx


Homework Equations


sec^2 (x)= 1+tan^2(x)


The Attempt at a Solution


=∫(1+tan^2 (x) or tan (x) tan (x)) tan (x) dx u=tan x, du=sec^2 dx

∫ (1+u^2) u du

= ∫u+u^2)du
= u^2/2 + u^3/3 = 1/2 tan^2(x)+ 1/3 tan^3 (x) +c

the answer in the back of the book is 1/2 tan^2(x)+c

what did i do wrong
 
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You didn't need to use this identity: sec2 (x)= 1+tan2(x)

u=tan x, du=sec^2 dx <-- This is an ideal start

[tex]\int tan(x) (sec^2(x) dx)[/tex]



Do you see where to replace your tan(x) as u and so on now?
 

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