Official GMATprep trial exam question 4
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There's a nice rule that says √(xy) = (√x)(√y)
For example √(16*49) = (√16)(√49) = (4)(7) = 28
Since a² - b² = (a + b)(a - b), can use the above rule to conclude that...
its √[a² - b²] = √[(a+b)(a-b)] = [√(a+b)][√(a-b)] = D
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Simplifying the given expression, we have:
√[(a + b)(a - b)] = √(a + b) x √(a - b)
Answer: D
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Hi All,
This question has a great Geometry 'shortcut' built into it - but you have to recognize that the calculation is a variation on the Pythagorean Theorem (re: A^2 + B^2 = C^2). If you notice that, then you can TEST VALUES (using the classic 3/4/5 right triangle for the values). Here, that would be....
A = 5
B = 4
and the result of the calculation is 3. You'll find that only one answer matches...
Final Answer: [spoiler=]D[/spoiler]
GMAT assassins aren't born, they're made,
Rich
This question has a great Geometry 'shortcut' built into it - but you have to recognize that the calculation is a variation on the Pythagorean Theorem (re: A^2 + B^2 = C^2). If you notice that, then you can TEST VALUES (using the classic 3/4/5 right triangle for the values). Here, that would be....
A = 5
B = 4
and the result of the calculation is 3. You'll find that only one answer matches...
Final Answer: [spoiler=]D[/spoiler]
GMAT assassins aren't born, they're made,
Rich