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Hello I came across a math equation and I was wondering what did the "e" stand for? the equation is : y=47931x-1E+0.8 Can someone please help me by showing what the E stands for and the answer for my equation. I know that I need to sub in a point for x so the only thing stopping me from answering the question is what to do for the 1E+0.8 part.

fred
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    It is scientific notation, the e or E stands for $10^x$ where x is the number following the e/E – Triatticus Feb 11 '17 at 19:33
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    Are you sure it is $E+0.8$? That decimal point seems unlikely. – Thomas Andrews Feb 11 '17 at 19:43
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    Can you write down exactly what the expression said. Is "x" the letter $x$ or the times symbol $\times$. I s the E capitolized or not. And what was the equation? Was this a math book? A chemistry book? What was the equation supposed to mean? And were any of the terms "rised" ? $1E$ vs $1^E$ or ... whatever. – fleablood Feb 11 '17 at 19:49
  • Why was this question upvoted? The tags are all wrong! We do not know whether $x$ in the equation is a variable or just the times symbol. The question is not clear! – Alex Silva Feb 11 '17 at 21:56

2 Answers2

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If it's a capital E, it should be scientific notation, specifically E notation.

Because 100,000,000 takes up a lot of space and can be difficult to compare with other numbers, it's written as $1$x$10^8$. Some calculators (and some books, to match) write this with an E:

Avogadro's constant in E notation By PRHaney - Own work, CC BY-SA 3.0

But that's done with integers, and you have $0.8$, so it must be

$$y = 47931x - e^{0.8},$$

using the natural exponential function.

Note that you can use lowercase e for scientific notation, but capital E should not be used for the natural exponential function.

MissMonicaE
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E = Exponentiation in base $10$.

Examples:

$$1.23\ \text{E+0.2} = 1.23\cdot 10^{0.2}$$

$$1.23\ \text{E-2.1} = 1.23\cdot 10^{-2.1}$$

Enrico M.
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    But you you must admit the use of a decimal, while not theoretically impossible is highly unusual. The usual point of scientific notation is to shift decimal points so it is usually always done iwht positive or negative integers. – fleablood Feb 11 '17 at 21:11
  • Yes, indeed is quite strange. I just gave a generalisation of the meaning, but I wouldn't ever expect a non integer exponential! – Enrico M. Feb 11 '17 at 22:43
  • This is probably the correct interpretation (I'm having a hard time thinking of any other) but I think we need to clarify where the OP read the expression and was it actually written as such. Hypothetically $y = 47931x - 1E+0.8$ could mean $y = 47931x - 10^{0.8} = 47931x - \sqrt[5]{10,000}$ but that would be .... weird. – fleablood Feb 11 '17 at 23:03