Question

to write 5.755x10^-4 in scientific notation=-.0005755?

Answer 1

Yup, you got it! To help with legibility, I often try to use a leading zero to the left of the decimal:
-0.0005755
that's more conventional and helps old people like us see the decimal better :-)

Answer 2

The number you have is correct, except the answer is positive, not negative.

Answer 3

.0005.755

Answer 4

0 to be eliminated

Answer 5

Answer is 0.0005755

Answer 6

0.0005755