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In this video, we are going to be dealing with the concept of elasticity of demand.
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And for those of you that need a quick refresher, we know that our elasticity of demand simply represents how a percent change and the price of a good or service can affect the consumer's demand for that good or service.
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We also know that if we're given our demand function in the form x is equal to fp, where p is our price, that our elasticity of demand, or our e of p, if you want to write it over here to the side, our e of p is going to be equal to negative p times f prime of p over f of p.
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We also know that if our efp is greater than one, our demand is going to be elastic.
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If it's equal to one, our demand is going to be unitary, and that if it's inelastic, our efp is going to be less than one.
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So in this question, what they've done is that they've given us our demand function in the form x is equal to f of p.
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So let's work for us.
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It is x is equal to negative 5 over 4p plus 20.
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And we've seen that they've also given us our p value of 10, so a price of $10.
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What they want us to do here is to use our elasticity of demand function and to determine if our demand is elastic, unitary, or inelastic at our p.
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So that's what we're going to do.
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We're going to start off with finding our efp.
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And we know that that's going to be equal to our p times our f prime of p...