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How do I evaluate composite functions?

Suppose you have 2 functions: f(x) = 3x 2 , g(x) = log 3 (x). These are arbitrary, any functions would work. Evaluate f(g(x)): let y = log 3 (x) ( = g(x) ), then f(g(x)) = f(y) = 3y 2 = 3[log 3 (x)] 2 . The ...
SG
Answered by Seb G. • Maths tutor
5088 Views

How do I differentiate implicitly?

The most important thing to remember when differentiating implicitly is that y is a function of x. Rewriting y as y(x) often makes it much clearer. For example, evaluate d/dx (y 2 ): using the aforementioned...
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Answered by Seb G. • Maths tutor
5373 Views

A cup of coffee is cooling down in a room following the equation x = 15 + 70e^(-t/40). Find the rate at which the temperature is decreasing when the coffee cools to 60°C.

First, we need to find the value of t when x = 6p°C. We are told that after t minutes the temperature, x, will be 60°C; so we can insert 60 into the equation for x: 60 = 15 + 70e^(-t/40) Secondly, we can rea...
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Answered by Nathan A. • Maths tutor
12615 Views

How do you revise for an English Literature exam?

Ah yes, the question which haunted my years of study, particularly during GCSE and A Levels. At this stage, many exams are ‘open book’ - that is, you can take either a blank or highlighted copy of the text i...
SP
14505 Views

What is the difference between oxidation and reduction?

In chemistry if a substance is oxidised it loses electrons in a reaction. If a substance is reduced it gains electrons in a reaction. A reaction that has both oxidation and reduction within it is called a RE...
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Answered by Thomas C. • Chemistry tutor
30711 Views