If (a + b + c) = 13, and (ab + bc + ca) = 54, find the value of (a² + b² + c²).
2023
If (a + b + c) = 13, and (ab + bc + ca) = 54, find the value of (a² + b² + c²).
- A.
63
- B.
65
- C.
61
- D.
59
Attempted by 51 students.
Show answer & explanation
Correct answer: C
(a + b + c)^2 = a^2 + b^2 + c^2 + 2(ab + bc + ca). Therefore a^2 + b^2 + c^2 = 13^2 - 2 x 54 = 169 - 108 = 61.