passwella.
Menu

JAMB Mathematics 1979 Question 17

Question 17

Surds

Rationalize the denominator of the expression (6 + 2√5)/(4 − 3√6)

  1. A.(24 + 3√5 + 7√6 + 9√30)/36
  2. B.−(24 + 8√5 + 18√6 + 6√30)/43
  3. C.(12 + 4√5 + 7√6 + 3√30)/17
  4. D.−(15 + 3√5 + 18√6 + 7√30)/39
  5. E.−(12 + 4√5 + 9√6 + 3√30)/19
Show the answer and explanation

Answer: E (−(12 + 4√5 + 9√6 + 3√30)/19)

Explanation

Multiply top and bottom by 4 + 3√6. The bottom becomes 16 − 54 = −38 and the top 24 + 18√6 + 8√5 + 6√30. Dividing by −38 gives −(12 + 4√5 + 9√6 + 3√30)/19.