What is the value of a² + b² + c² if a + b + c = 12 and ab + bc + ca = 40?
Show answer & explanation
Correct answer: B
Explanation
a + b + c = 12
ab + bc + ca = 40
According to the formula:
(a + b + c)² = a² + b² + c² + 2(ab + bc + ca)
(12)² = a² + b² + c² + 2(40)
144 = a² + b² + c² + 80
a² + b² + c² = 144 − 80= 64