- #1
GunnaSix
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Homework Statement
Let [tex]V=x^3[/tex]
Find [tex]dV[/tex] and [tex]\Delta V[/tex].
Show that for very small values of [tex]x[/tex] , the difference
[tex]\Delta V - dV[/tex]
is very small in the sense that there exists [tex]\varepsilon[/tex] such that
[tex]\Delta V - dV = \varepsilon \Delta x[/tex],
where [tex]\varepsilon \to 0[/tex] as [tex]\Delta x \to 0[/tex].
Homework Equations
[tex]dV = 3x^2 dx[/tex]
[tex]\Delta V = 3x^2 \Delta x + 3x (\Delta x)^2 + (\Delta x)^3[/tex]
The Attempt at a Solution
I worked it down to
[tex]\varepsilon = 3x \Delta x + (\Delta x)^2 + 3x^2 \left(1 - \frac{dx}{\Delta x} \right)[/tex]
Can I say that [tex]\lim_{\Delta x \to 0} \Delta x = dx[/tex] so that
[tex]\lim_{\Delta x \to 0} \varepsilon = 3x(0) + (0)^2 + 3x^2(1-1) = 0[/tex] ?