If a and b are the roots of the equation x2 - 5x + 5 = 0, then the value of a2 + b2 is:
Options
A) 36
B) 24
C) 15
D) 6
E) 5

Rationale: "sol . ( b ) the sum of roots = a + b = 5 product of roots = ab = 5 now , a 2 + b 2 = ( a + b ) 2 - 2 ab = 25 - 10 = 15 answer c"
Answer: C