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GRE Math Strategies Part VI of VI: Elimination

If two or more choices can be eliminated, make an educated guess among the remaining answer choices. When possible, try to reduce the guessing to among two or three choices.
Use this approach sparingly and only when pressed for time.

Which of the following cannot be simplified further?
(A) sqrt{1}
(B) sqrt{18}
(C) sqrt{3}*sqrt{2}
(D) sqrt{5}+sqrt{11}
(E) 4sqrt{4}

(D) is the correct answer.
We can best solve this problem by the Elimination approach. Look carefully at each answer choice and try to eliminate all but one.
We can simplify a square root if it contains a perfect square. In this problem we can simplify (A), (B), and (E) by recognizing the perfect squares they contain:
(A) sqrt{1} = 1
(B) sqrt{18} = sqrt{9*2}=sqrt{9}*sqrt{2}=3sqrt{2}
(C) Simplify by multiplying: sqrt{3}*sqrt{2} = sqrt{3*2} = sqrt{6}
(D) Different numbers are under the square root sign, so they cannot be added. Furthermore, neither radical can be simplified.
(E) 4sqrt{4} = 4*2 = 8

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