Evaluate expression W/O Calculator

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SUMMARY

The expression \sqrt[3]{10+6\sqrt{3}}+\sqrt[3]{10-6\sqrt{3}} can be evaluated using the identity for the sum of cubes. By letting x = \sqrt[3]{10+6\sqrt{3}}+\sqrt[3]{10-6\sqrt{3}}, the equation simplifies to x^3 + 6x - 20 = 0. The Rational Root Theorem reveals that the only real solution is x = 2, confirming that the exact value of the expression is 2.

PREREQUISITES
  • Understanding of cube roots and their properties
  • Familiarity with the Rational Root Theorem
  • Knowledge of binomial expansion, specifically (a+b)^3
  • Ability to manipulate and solve cubic equations
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  • Study the Rational Root Theorem and its applications in polynomial equations
  • Learn about binomial expansion and its relevance in algebraic simplifications
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  • Explore advanced topics in algebra such as surds and their simplifications
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Students, educators, and anyone interested in algebraic problem-solving, particularly those dealing with cubic equations and radical expressions.

  • #31
S.R said:
I didn't notice that; thanks!

x^3-6x-20=0

(x-2)(x^2+2x+10) = 0

The only real solution is x=2.

Yeah, well done! :approve:

EDIT: Small correction: the equation should've been x^3 + 6x - 20 = 0. Small matter, just a typo. :smile:
 

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