[" 4.Which of the following equations has the sum of its roots as "3?],[[" (a) "2x^(2)-3x+6=0," (b) "-x^(2)+3x-3=0],[" (c) "sqrt(2)x^(2)-(3)/(sqrt(2))x+1=0," (d) "3x^(2)-3x+3=0]]