a + b + c = 9 এবং ab + bc + ca = 31 হয়, তবে a2+b2+c2=?
A
19
B
20
C
17
D
18
Correct Answer: 19
Given that,a + b + c = 9ab + bc + ca = 31Find out, a2 + b 2 + c2 =?= (a + b + c)2 - 2(ab + bc + ca)= 92 - 2 × 31= 19