Question

hey guys i wanna quick solution with full explanation if dont know no need to answer ​

Answer 1

Answer:

2√42 is the answer ok

but follow me

Answer 2

Answer:

$d = \sqrt{ {( \sqrt 42)}^{2} + {( - \sqrt 42)}^{2} } \\ = \sqrt{42 + 42 } \\ = \sqrt{84} = \sqrt{2 \times 2 \times 21} \\ = 2 \sqrt{21}$