(10 Squar root -13)(-5 square root -5)

Question

put in standard form a+bi

I really don't understand square roots so can you show me how to do these please

Answer 1

by definition √-1 = i

so rewrite
(10√-13)(-5√-5) as

(10√-1√13)(-5√-i√5)
= (10i√13)(-5i√5)
= -50i^2√65
= +50√5