The square root of (7+3 √(5))(7-3 √(5)) is · ABC26GN1409

Subject: General Aptitude · Chapter: Square Roots and Cube Roots · Exam: S.S.C. 2004

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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