What is the value of x?
- x 2 - 9 = 0
- x 2 + 6x + 9 = 0
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Statement (1) BY ITSELF is sufficient,
but statement (2) by itself is not sufficient. |
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Statement (2) BY ITSELF is sufficient,
but statement (1) by itself is not sufficient. |
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Both statements TAKEN TOGETHER
are sufficient, but NEITHER statement BY ITSELF is sufficient. |
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EACH statement BY ITSELF is sufficient. |
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The two statements TAKEN TOGETHER are NOT
sufficient.
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Countinue
Each statement provides you with a quadratic equation which means that
each statement will yield two values for x. The first thing to
note is that this Data Sufficiency is a value question, so, as you've
learned, to be sufficient a statement must lead to one and only one
value.
This is a classic GMAT trap! Statement (1) yields two different values,
3 and –3. Statement (2) also yields two values, but the values
are identical.
Solving for x we find that x = –3 or x = –3, so we find one
and only one value. Thus, Statement (2) is sufficient.
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