Expansion of exponentials (very easy)

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SUMMARY

The discussion centers on the expansion of the expression (e^x + e^-x)^2, leading to the result e^2x + 2 + e^-2x. The confusion arises from understanding the "+2" term in the final expression. Participants clarify that the expansion follows the formula (a+b)^2 = a^2 + 2ab + b^2, emphasizing the importance of using the FOIL method correctly to derive the terms. The correct application of this method confirms the presence of the "+2" in the final result.

PREREQUISITES
  • Understanding of exponential functions, specifically e^x and e^-x.
  • Familiarity with algebraic expansion techniques, particularly the FOIL method.
  • Knowledge of basic algebraic identities, such as (a+b)^2.
  • Ability to manipulate and simplify algebraic expressions.
NEXT STEPS
  • Study the FOIL method in greater detail to enhance algebraic expansion skills.
  • Practice expanding other exponential expressions using similar techniques.
  • Explore the properties of exponential functions and their applications in calculus.
  • Learn about binomial expansions and their relevance in higher mathematics.
USEFUL FOR

Students and educators in mathematics, particularly those focusing on algebra and calculus, as well as anyone looking to strengthen their understanding of exponential functions and algebraic expansions.

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Sorry, I'm having a severe mental block here, sorry if this is laughable.

Question
Expand (e^x + e^-x)^2

I've got the answer but I'm just stumped at how to reach it, I don't know where the 2 comes from:

Answer
e^2x + 2 + e^-2x

Thanks (and sorry again)
 
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Are you unsure how to even start or is there a particular term you are confused about? Which 2 are you talking about, the +2 or the 2 in e^2x?
 
eok20 said:
Are you unsure how to even start or is there a particular term you are confused about? Which 2 are you talking about, the +2 or the 2 in e^2x?

Sorry, the +2. I can reach the e^2x + e^-2x but I can't reach the "+2" which means the method I'm using is incorrect.

I haven't touched this stuff in a while so I'm just trying to re-remember it.
 
Remember, (a+b)^2 = a^2 + 2ab + b^2 (use foil), NOT a^2 + b^2
 
eok20 said:
Remember, (a+b)^2 = a^2 + 2ab + b^2 (use foil), NOT a^2 + b^2

Yeah, i tried using foil.

Foil if I'm not mistaken would grant me.

(e^x + e^-x) (e^x + e^-x)

(e^x * e^x) + (e^x * e^-x) + (e^-x * e^x) + (e^-x * e^-x)

(e^2x) + (1) + (1) + (e^-2x)

(e^2x) + (2) + (e^-2x)

Is that right?
 
Yep, looks good.
 
aha, thanks for the help. Just got a bit confused with the powers for a moment it seems.
 

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