ps - inequalities

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ps - inequalities

by ccassel » Wed Mar 30, 2011 11:53 am
Which of the following inequalities has a solution set that, when graphed on the number line is a singel line segment of finite length?

1. x^4 > 1
2. x^3 <= 27
3. x^2 >= 16
4. 2 <= |x| <=5
5. 2 <= 3x+4 <= 6
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by gmat-challenger » Wed Mar 30, 2011 12:42 pm
5. -2/3 <= x <= 2/3

that's a single line with a beginning at -2/3 and end at 2/3

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by ccassel » Wed Mar 30, 2011 1:04 pm
Can you explain how you came about this solution?

Thanks,

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by GMATGuruNY » Wed Mar 30, 2011 1:41 pm
ccassel wrote:Which of the following inequalities has a solution set that, when graphed on the number line is a singel line segment of finite length?

1. x^4 > 1
2. x^3 <= 27
3. x^2 >= 16
4. 2 <= |x| <=5
5. 2 <= 3x+4 <= 6
The equation of a line generally doesn't include exponents or absolute value.
The most linear-looking answer choice is E.

E simplified:
Start: 2 ≤ 3x+4 ≤ 6
Subtract 4 from each part: -2 ≤ 3x ≤ 2
Divide each part by 3: -2/3 ≤ x ≤ 2/3

The inequality -2/3 ≤ x ≤ 2/3 represents a line segment: namely, every point on the number line between -2/3 and 2/3, inclusive.

The correct answer is E.
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