I was sifting through the beginning of my book when i came upon a section based on marginals and differentials. My question is why does Δy/Δx ≈ f'(x) when the lim Δx →0 Δy/Δx = f'(x)?(adsbygoogle = window.adsbygoogle || []).push({});

Δx = (x + Δx) - x ; therefore, Δy = f(x + Δx) - f(x) .

Δy/Δx = {f(x + Δx) - f(x)}/ Δx ≈ f'(x)

f'(x) = lim {f(x + Δx) - f(x)}/ Δx

Δx→0

In simplest terms, why does the lim Δx →0 change the ≈ to =?

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# Why does the lim Δx →0 change the ≈ to =?

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