ABC26GN1396 · Square Roots and Cube Roots
Subject: General Aptitude · Chapter: Square Roots and Cube Roots · Exam: · Marks: · Difficulty:
If $3 \sqrt{5}+\sqrt{125}=17.88$, then what will be the value of $\sqrt{80}+6 \sqrt{5}$ ?
(a)13.41
(b)20.46
(c)21.66
(d)22.35
Answer
Explanation
$$\begin{aligned} & 3 \sqrt{5}+\sqrt{125}=17.88 \Rightarrow 3 \sqrt{5}+\sqrt{25 \times 5}=17.88 \\ & \Rightarrow 3 \sqrt{5}+5 \sqrt{5}=17.88 \Rightarrow 8 \sqrt{5}=17.88 \Rightarrow \sqrt{5}=2.235 . \\ & \therefore \quad \sqrt{80}+6 \sqrt{5}=\sqrt{16 \times 5}+6 \sqrt{5}=4 \sqrt{5}+6 \sqrt{5} \\ & \quad=10 \sqrt{5}=(10 \times 2.235)=22.35 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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