imaginary numbers questionnn?

Question

1. the square root of -42 times the square root of -6
2. the square root of -16/25
3. the square root of -8/3

Answer 1

What am I missing?

Answers to question presented:

1) 15.8745078663875
2) 0.8
3) 1.6329931618554520654648560498039

Answer 2

Question 1
√( i ² 42) x √ ( i ² 6 )
i √42 x i √6
i² √252
i² 2 √63
i² x 2 x 3√7
- 6 √7
Question 2
√ i ² (16/25)
(4/5) i

Question 3
√ i ² (8/3)
2√2 i / √3
(2/3) (√2)(√3) i
(2/3) √6 i

Answer 3

1. the square root of -42 times the square root of -6
= (sqrt42)i * (sqrt6)i
= -1 (sqrt6*7)(sqrt6)
= -1 (sqrt 6*7*6)
= -6 sqrt 7

2. the square root of -16/25
= (4/5)i

3. the square root of -8/3
= [sqrt(8/3)]i
= [2sqrt(2/3)]i

Answer 4

1. i*sqrt(42) * i*sqrt(6)
i*sqrt(252)
2i*sqrt(63)
6i*sqrt(7)

2. i*sqrt(16/25)
i*(4/5)
4i/5

3. i*sqrt(8/3)

Answer 5

1.- = -15.875
2.- = 0.8i
3.- = 1.633i