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How to solve root questions.

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Source: — Problem Solving |

by Anju@Gurome » Sun Apr 21, 2013 5:20 am
karan.7045 wrote:How to solve the root questions ,For example wat is the value of root 4 + cubth root of 4 + 4th root of 4.
I got stuck on a similar kind of question on GMAT
GMAT will never ask to find out the exact value of that.
The problem you are talking about is as follows,
If M = (square root of 4 + cube root of 4 + fourth root of 4), then the value of M is:

A. Less than 3
B. Equal to 3
C. Between 3 and 4
D. Equal to 4
E. Greater than 4
To answer this problem, we only need an estimation of the value.
As 4 > 1, any root of 4 will be greater than 1.
Now, square root of 4 = 2
Cube root of 4 will be greater than 1 but less than square root of 2.
So, 1 < cube root of 4 < 2
Similarly, 1 < fourth root of 4 < 2

Hence, M must be greater than (2 + 1 + 1) = 4

The correct answer is E.
Anju Agarwal
Quant Expert, Gurome

Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.

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by karan.7045 » Sun Apr 21, 2013 5:24 am
Thanku so much.. Its really helpful .. I got the same question in the exam.
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