What am I plugging in wrong for find the average rate of change? g(x)=?

My work. Why does it = 353/27?
View attachment 19635
g(-1) = 6*(-1)2 + \(\displaystyle \frac{4}{-1^3} \ \)

= 6 * (-1) * (-1) + \(\displaystyle \frac{4}{(-1) * (-1) * (-1)} \ \)

= (6) + \(\displaystyle \frac{4}{(-1)} \ \)

= 6 - 4

= 2 (positive number)

There are more mistakes. Work all the way with fractions - since the required answer is in fraction. Do not convert to decimals.

Please check your arithmetic - carefully.
 
None of what you wrote down makes any sense.

[MATH]g(x) = 6x^2 + \dfrac{4}{x^3} = \dfrac{6x^5 + 4}{x^3} \implies \\ g(-1) = \dfrac{6(-1)^5 + 4}{(-1)^3} = \dfrac{- 6 + 4}{- 1} = \dfrac{-2}{-1} = 2 \text { and } \\ g(3) = \dfrac{6(3^5) + 4}{3^3} = \dfrac{6 * 243 + 4}{27} = \dfrac{1458 + 4}{27} = \dfrac{1462}{27}.\\ \therefore \dfrac{2 - \dfrac{1462}{27}}{-1 - 3} = \dfrac{- \dfrac{1408}{27}}{-4} = \dfrac{1408}{27} * \dfrac{1}{4} = \dfrac{352}{27} [/MATH]
 
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None of what you wrote down makes any sense.

[MATH]g(x) = 6x^2 + \dfrac{4}{x^3} = \dfrac{6x^5 + 4}{x^3} \implies \\ g(-1) = \dfrac{6(-1)^5 + 4}{(-1)^3} = \dfrac{- 6 + 4}{- 1} = \dfrac{-2}{-1} = 2 \text { and } \\ g(3) = \dfrac{6(3^5) + 4}{3^3} = \dfrac{6 * 243 + 4}{27} = \dfrac{1458 + 4}{27} = \dfrac{1462}{27}.\\ \therefore \dfrac{2 - \dfrac{1462}{27}}{-1 - 3} = \dfrac{- \dfrac{1408}{27}}{-4} = \dfrac{1408}{27} * \dfrac{1}{4} = \dfrac{352}{27} [/MATH]
But why raise it to the power of 5?
 
But why raise it to the power of 5?
I don't like adding numerical fractions because I make mistakes. So I did it algebraically to simplify my arithmetic.

[MATH]g(x) = 6x^2 + \dfrac{4}{x^3} = \dfrac{6x^2 * x^3}{x^3} + \dfrac{4}{x^3} = \dfrac{6x^{2+3} + 4}{x^3} = \dfrac{6x^5 + 4}{x^3}.[/MATH]
It is just a slightly different way to state the function. But your problem was (a) multiple errors in arithmetic and (b) apparent lack of understanding of function notation. If you are starting calculus, you need a rapid but deep review of functions because 95% of the course involves working with them.
 
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