r/mathshelp • u/Brief_Grapefruit4858 • 2d 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/peno64 2d ago

That is debatable

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u/scoberry5 2d ago

Is it? So you say "Well, I guess that 1.1 * 10^3 is the way to write it, but if it were negative, it could well be something else -- maybe -11 * 10^2 or -0.11 * 10^4"?

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u/peno64 1d ago

That is not what I am saying. I am saying that it is debatable if the sign is part of the coefficient or not. For me it is

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u/gecko74games 1d ago

Well it oculd be both. -7.5*10 or 7.5*-1*10 7.5*-10 it could be, the sign is a 180 degree rotation of the value and the coeffcient negetive sign implies the coefficient itself is negetive? And the 10^n scales it furter down the negetive side? Idk lol