Question -
Answer -
Which of the following equations has the sumof its roots as 3?
(A) 2x2 – 3x + 6 = 0 (B) –x2 +3x – 3 = 0
(C) √2x2 – 3/√2x+1=0 (D) 3x2 –3x + 3 = 0
Solution:
(B) –x2 + 3x – 3 = 0
The sum of the roots of a quadratic equationax2 + bx + c = 0, a ≠ 0 is given by,
Coefficient of x / coefficient of x2 =– (b/a)
(A) Given, 2x2 – 3x + 6 = 0
Sum of the roots = – b/a = -(-3/2) = 3/2
(B) Given, -x2 + 3x – 3 = 0
Sum of the roots = – b/a = -(3/-1) = 3
(C) Given, √2x2 –3/√2x+1=0
2x2 – 3x + √2 = 0
Sum of the roots = – b/a = -(-3/2) = 3/2
(D) Given, 3x2 – 3x + 3 = 0
Sum of the roots = – b/a = -(-3/3) = 1