Question

Pick out the irrational number from the following numbers: Select one: a. √7 / √28 b. √40 / √20 c. 1 / √ 9 d. - √49

Answer 1

Answer:

$b) \frac{ \sqrt{40} }{ \sqrt{20} }$

Step-by-step explanation:

$a) \frac{ \sqrt{7} }{ \sqrt{28} } = \frac{ \sqrt{7} }{2 \sqrt{7} } = \frac{1}{2} \: \: is \: \: rational.$

$b) \frac{ \sqrt{40} }{ \sqrt{20} } = \frac{ \sqrt{4} }{ \sqrt{2} } = \frac{2}{ \sqrt{2} } \: \: \: is \: \: irrational.$

$c) \frac{1}{ \sqrt{9} } = \frac{1}{3} \: \: is \: \: rational.$

$d) - \sqrt{49} = - 7 \: \: is \: \: rational.$

$Therefore, \: \: b) \frac{ \sqrt{40} }{20} \: \: is \: \: irrational.$