Question

5.

Which of the following equations has the sum of its roots as 3?
(A) 2x² – 3x + 6 = 0
(B) - x²+ 3x - 3 = 0
(C)√2x²-3/√2x+1
(D) 3x² – 3x + 3 = 0​

Answer 1

B

Explanation:

Given a quadratic equation in standard form, ax² + bx + c = 0 ( a ≠ 0 )

Then the sum of the roots = -
`(b)/(a)`

A 2x² - 3x + 6 = 0

with a = 2 and b = - 3

sum of roots = -
`(-3)/(2)` =
`(3)/(2)` ≠ 3

B - x² + 3x - 3 = 0

with a = - 1 and b = 3

sum of roots = -
`(3)/(-1)` = 3 ← True

C
`√(2)` x² -
`(3)/(√(2) )` x + 1

with a =
`√(2)` and b = -
`(3)/(√(2) )`

sum of roots = -
`(-(3)/(√(2) ) )/(√(2) )` =
`(3)/(2)` ≠ 3

D 3x² - 3x + 3 = 0

with a = 3 and b = - 3

sum of roots = -
`(3)/(-3)` = 1 ≠ 3

Thus the equation with sum of roots as 3 is B