Question

Prove that if the square of a number m is a multiple of 3, then the number m is also a multiple of 3.

Answer 1

According to question,

m² = 3λ, where λ is an integer

$∴m = \sqrt{3 λ} \\∴m = \frac{3λ}{ \sqrt{3} } = 3 \times \frac{λ}{ \sqrt{3} }$

Hence, m is also an integer.