How to solve this question

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For a quadratic equation of the form x2 +bx + c, describe all x for which f(x + 3) = f(-2x)?

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Hi shibsriz,

This question is missing at least one relevant piece of information, the most obvious of which is that it refers to a "quadratic equation" but there is NO EQUATION. Is the equation set equal to 0, a different number, another expression with variables? In addition, you should include the 5 answer choices for reference.

GMAT assassins aren't born, they're made,
Rich

[Matt@VeritasPrep]

Hi Shibsriz!

Let's clarify the question a bit here. If f(x) is defined as f(x) = x^2 + bx + c, then the question is really asking "For what values of x is (x+3)^2 + (x+3)b + c = (-2x)^2 + (-2x)*b + c?"

Simplifying the equation, that gives us

x^2 + 6x + 9 + bx + 3b + c = 4x^2 - 2bx + c

or

3bx + 3b - 3x^2 + 6x + 9 = 0

or

3 * (x+1) * (b - x + 3) = 0

or

x = -1, x = b + 3

But this doesn't really feel like a GMAT question to me - it's more of a high school math olympiad sort of question.