Manhatten GMAT Test explanation

[thegreatking]

What is the value of x?

(1) x^2 + 5x + 6 = 20

(2) x < 0
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(1) INSUFFICIENT: Solve the quadratic equation by factoring it as follows:

x^2 + 5x + 6 = 20
x^2 + 5x - 14 = 0
(x - 7)(x + 2) = 0

Therefore the solutions to the original quadratic are x = 7 and x = -2. Since there are two different possible values for x, statement (1) is insufficient.

(2) INSUFFICIENT: This tells us only that x is less than 0; it does not give us a unique value for x.

(1) AND (2) SUFFICIENT: Statement (1) tells us that x = 7 or x = -2. Statement (2) says that x < 0, so x must equal -2.
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Isn't x^2 + 5x - 14 = (x + 7)(x - 2) rather than (x - 7)(x + 2) = 0

[esledge]

Isn't x^2 + 5x - 14 = (x + 7)(x - 2) rather than (x - 7)(x + 2) = 0

You are right; we'll make sure to edit that explanation. Incidentally, the answer (C)and basic logic are still the same (i.e. statement (1) gives both a pos and neg solution, (2) eliminates the negative solution, leaving only one positive solution when the statements are combined).

Thanks for catching that!