Question

Find the square root by prime factorisation:
i) $196$
ii) $225$

• A. $14,25$
• B. $14,15$
• C. $24,15$
• D. $24,25$

Answer 1

Answer: (B)

$14,15$

(1)

$196=2\times 2\times 7\times 7$

$\sqrt{196}=\sqrt{2\times 2\times 7\times 7}$

$=\sqrt{2^2\times 7^2}$

$=2\times 7$

$=14$

(2)

$225=3\times 3\times 5\times 5$

$\sqrt{225}=\sqrt{3\times 3\times 5\times 5}$

$=\sqrt{3^2\times 5^2}$

$=3\times 5$

$=15$