Question

How does the square root of 4 + 16 turn into 2 times the square root of 5? www.mathportal.org/calculators/analytic-geometry/distance-and-midpoint-calculator.php?val1=3&val2=-2&val3=1&val4=-6&rb1=dist
( at the bottom )

Answer 1

please note that:
\[\sqrt{4+16}=\sqrt{20}=\sqrt{4*5}=\sqrt{2^{2}*5}=2\sqrt{5}\]

Answer 2

@mizuno

Answer 3

Thanks! @Michele_Laino

Answer 4

Thanks! @mizuno