Chapter 5: Problem 30
a. Verify by multiplication that \((x+1)\left(x^{2}-x+1\right)=x^{3}+1\) b. Use the factors of \(x^{3}+1\) to find the three roots of \(\mathrm{f}(x)=x^{3}+1\) c. If \(x^{3}+1=0,\) then \(x^{3}=-1\) and \(x=\sqrt[3]{-1}\) Use the answer to part \(\mathbf{b}\) to write the three cube roots of \(-1 .\) Explain your reasoning. d. Verify that each of the two imaginary roots of \(f(x)=x^{3}+1\) is a cube root of \(-1\)
Short Answer
Step by step solution
Expand the Left Side
Factor to Find the Roots
Cube Roots of -1
Verify Imaginary Roots
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Factorization
Complex Numbers
Quadratic Formula
Cube Roots
- Real root: \(-1\)
- \(x = \frac{1 + i\sqrt{3}}{2}\)
- \(x = \frac{1 - i\sqrt{3}}{2}\)