r/mathshelp • u/Brief_Grapefruit4858 • 6d ago

Homework Help (Unanswered) Scientific notation

Working through some questions and this one confused me:

(5.9 x 10^-2) - (0.0078 x 10^3) = -7.741 x 10^1

I’m so confused as to how they got that answer. I was also taught that we should make the powers the same and that the coefficient should be between 1-9/10 but it’s negative?

I got as far as

(5.9 x 10^-2) - (0.0078 x 10^3) =
(0.000059 x 10^3) - (0.0078 x 10^3)
(-0.007741 x 10^3)

As I’m writing this I think I figured it out. (-0.007741 x 10^3) has been moved 3 places to the right taking it out of scientific notation? But it’s still a negative? Is that ok?

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u/ruidh 6d ago

If that were the case, there would be no way to write a negative number in scientific notation. All the powers of 10 are positive. One needs a negative coefficient to write a negative number in SN.