If the sum of a number and its reciprocal is 15. What is the sum of the square of the number and the square of its reciprocal?
Show answer & explanation
Correct answer: A
Explanation
Let the number be x.
x + 1/x = 15
Squaring both sides,
x² + 1/x² + 2 = 15²
x² + 1/x² = 225 − 2 = 223
= 111 × 2 + 1