If a and b are the roots of the equation x2 - 9x + 9 = 0, then the value of a2 + b2 is:
Choose the correct choice from the following answers:
A) 63
B) 24
C) 17
D) 6
E) 5

Rationale: "sol . ( b ) the sum of roots = a + b = 9 product of roots = ab = 9 now , a 2 + b 2 = ( a + b ) 2 - 2 ab = 81 - 18 = 63 answer a"
Answer: A