Carcass wrote:
Which of the following expressions is equivalent to \(\frac{6}{4+\sqrt{7}}\) ?
A \(\frac{2(4-\sqrt{7})}{3}\)
B \(\frac{6(4+\sqrt{7})}{23}\)
C \(\frac{(4-\sqrt{7})}{3}\)
D \(\frac{6(4-\sqrt{7})}{23}\)
To rationalize the denominator we must multiply numerator and denominator by \(4-\sqrt{7}\), which is the compliment of \(4+\sqrt{7}\)
We get: \(\frac{6(4-\sqrt{7})}{(4+\sqrt{7})(4-\sqrt{7})}\)
Expand and simplify the denominator: \(\frac{6(4-\sqrt{7})}{9}\)
Simplify by dividing numerator and denominator by \(3\) to get: \(\frac{2(4-\sqrt{7})}{3}\)
Answer: A