a+b+c=9 এবং ab + bc + ca =26 হলে a2+b2+c2 এর মান কত?
A
58
B
48
C
29
D
30
Correct Answer: 29
a + b + c = 9, ab + bc + ca = 26, a² + b² + c² = ? (a + b + c)² = a² + b² + c² + 2(ab + bc + ca) বা, a² + b² + c² = (a + b + c)² - 2(ab + bc + ca) = 9² - (2×26) = 81 - 52 = 29