A conjugate is formed by changing the operation between two terms in a binomial algebraic expression. Conjugates are commonly used to rationalize the denominator.
\((a+b)\) has a conjugate of \((a-b)\)
\((a-b)\) has a conjugate of \((a+b)\)
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\(\textbf{1)}\) Find the conjugate of \(4+\sqrt{2}\) The conjugate is \(4-\sqrt{2}\)
\(\textbf{2)}\) Find the conjugate of \(3+i\) The conjugate is \(3-i\)
\(\textbf{3)}\) Find the conjugate of \(5-i\) The conjugate is \(5+i\)
\(\textbf{4)}\) Simplify \(\displaystyle\frac{5}{3+\sqrt{3}}\) The answer is \(\displaystyle\frac{15-5\sqrt{3}}{6}\)
\(\,\,\,\,\,\displaystyle\frac{5}{3+\sqrt{3}} \cdot \frac{3-\sqrt{3}}{3-\sqrt{3}}\)
\(\,\,\,\,\,\displaystyle\frac{15-5\sqrt{3}}{9-3\sqrt{3}+3\sqrt{3}-3}\)
\(\,\,\,\,\,\displaystyle\frac{15-5\sqrt{3}}{9-3}\)
\(\,\,\,\,\,\displaystyle\frac{15-5\sqrt{3}}{6}\)
\(\textbf{5)}\) Simplify \(\displaystyle\frac{\sqrt{2}}{\sqrt{5}-1}\) The answer is \(\displaystyle \frac{\sqrt{10}+\sqrt{2}}{4}\)
\(\,\,\,\,\,\displaystyle\frac{\sqrt{2}}{\sqrt{5} – 1} \cdot \frac{\sqrt{5} + 1}{\sqrt{5} + 1}\)
\(\,\,\,\,\,\displaystyle\frac{\sqrt{2}(\sqrt{5} + 1)}{(\sqrt{5})^2 – (1)^2}\)
\(\,\,\,\,\,\displaystyle\frac{\sqrt{10} + \sqrt{2}}{5 – 1}\)
\(\,\,\,\,\,\displaystyle\frac{\sqrt{10} + \sqrt{2}}{4}\)
\(\textbf{6)}\) Simplify \(\displaystyle\frac{2+\sqrt{2}}{3-\sqrt{2}}\) The answer is \(\displaystyle \frac{8+5\sqrt{2}}{7}\)
\(\,\,\,\,\,\displaystyle\frac{2+\sqrt{2}}{3-\sqrt{2}} \cdot \frac{3+\sqrt{2}}{3+\sqrt{2}}\)
\(\,\,\,\,\,\displaystyle\frac{(2+\sqrt{2})(3+\sqrt{2})}{(3)^2 – (\sqrt{2})^2}\)
\(\,\,\,\,\,\displaystyle\frac{6 + 2\sqrt{2} + 3\sqrt{2} + 2}{9 – 2}\)
\(\,\,\,\,\,\displaystyle\frac{8 + 5\sqrt{2}}{7}\)
\(\textbf{7)}\) Simplify \( \displaystyle\frac{2i}{3+4i} \) The answer is \( \displaystyle\frac{6i+8}{25} \)
\(\textbf{8)}\) Simplify \( \displaystyle\frac{6+i}{3+2i} \) The answer is \( \displaystyle\frac{20-9i}{13} \)
\(\textbf{9)}\) Simplify \( \displaystyle\frac{3-2i}{4i} \) The answer is \( \displaystyle\frac{-(3i+2)}{4} \)
\(\textbf{10)}\) Simplify \( \displaystyle\frac{3}{i} \) The answer is \( -3i \)