Question: Rational Sum of Solutions

Comment on Rational Sum of Solutions


I would have chosen -1 as the answer but it says sum of all possible value that's why we add the 2 outcomes .
gmat-admin's picture

That's correct. -1 is only one of the two possible solutions. The other is -3. So, we must add the two solutions to get -1 + 3 = 2

Hi Brent,
Can we after seeing the value of b(square) - 4ac >0,
Directly deduce that since it is a quadratic equation and will be having two solutions (for such type of questions) ?
gmat-admin's picture

That's true, but in order to determine the sum, you still need to solve the equation.

We could use also the Vieta's formulas after we got that it is a quadratic equation with a equals 1. The sum of roots is -b.
gmat-admin's picture

Yes, that's absolutely correct. Good idea.


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