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Answers
A
B
C
D
E
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Difficulty—
If n and k are positive integers, is
$$\sqrt{n+k}>2\sqrt{n}?$$
$$\left(1\right)\ k>3n$$
$$\left(2\right)\ n+k>3n$$
The OA is A.
I think that it can be solved as follows:
$$\left(\sqrt{n+k}\right)^2>\left(2\sqrt{n}\right)^2\ \Rightarrow \ n+k\ >2n\ \Rightarrow \ k>3n.$$
Hence, statement 1 is sufficient.
$$\sqrt{n+k}>2\sqrt{n}?$$
$$\left(1\right)\ k>3n$$
$$\left(2\right)\ n+k>3n$$
The OA is A.
I think that it can be solved as follows:
$$\left(\sqrt{n+k}\right)^2>\left(2\sqrt{n}\right)^2\ \Rightarrow \ n+k\ >2n\ \Rightarrow \ k>3n.$$
Hence, statement 1 is sufficient.
