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Edexcel January 2007 - Question 4 (Rates and Differential Equations)

Rates and differential equations is a topic many students find difficult, especially when solving the differential equation is combined with techniques from other topics on the C4 syllabus. I hope my walkthr...
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Answered by Oliver V. • Maths tutor
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Find dy/dx from the equation 2xy + 3x^2 = 4y

Firstly we must notice that we can differentiate each term separately. Starting with the 2xy term, we must use the product rule as x and y are two variable that will differentiate. Setting u=2x and v=y and u...
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Answered by Murray M. • Maths tutor
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Rationalise the denominator of the fraction 3/sqrt(5)

In order to rationalise the denominator we need to get rid of the surd (square-root) on the bottom of the fraction. To do this, we can multiply the denominator by sqrt(5). But we must notice that to keep the...
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Answered by Murray M. • Maths tutor
20467 Views

Does the function y=x^3+x+(x^2+1)e^x have a horizontal tangent?

We want to determine whether a function has a tangent which is horizontal. To answer the question we need to know what a horizontal tangent to a function means. A tangent to a graph of a function is a line w...
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Answered by Daniel E. • Maths tutor
6831 Views

What is meant by the term 'opportunity cost'

This simply means, 'the next best alternative foregone'. We can explain this by saying if I only had £5 to buy lunch, I could either buy a sandwich or half a pizza. The opportunity cost of me buying a sandwi...
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Answered by KATIE C. • Economics tutor
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