{1/(4+√15)} = Pick one.
A) a. 16+16√15	B) b. 31- 8√15	C) c. 31+ 8√15	D) d. 4- √15	E) e. 32 + 4√15
= 1 / (4 + root15)   Multiply numeratordenominator by (4 - root15)   = (4 - root15) / (16-15) = (4 - root15)   Answer = d. 4- √15
<result>D</result>
{1/(4+√15)} =