ABC26GN1409 · Square Roots and Cube Roots

Subject: General Aptitude · Chapter: Square Roots and Cube Roots · Exam: 2004 · Marks: · Difficulty:

The square root of $(7+3 \sqrt{5})(7-3 \sqrt{5})$ is
(a)$\sqrt{5}$
(b)2
(c)4
(d)$3 \sqrt{5}$
Answer
Answer (as printed): B
Explanation
$$\begin{aligned} \sqrt{(7+3 \sqrt{5})(7-3 \sqrt{5})} & =\sqrt{(7)^{2}-(3 \sqrt{5})^{2}} \\ & =\sqrt{49-45}=\sqrt{4}=2 . \end{aligned}$$

Explanation as extracted from the printed page; notation may be imperfect.

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