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Maths
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Why does the chain rule work?

One of the best ways to view dy/dx is as a fraction. When we have y=f(g(x)), we need to make a substitution u=g(x) to find dy/dx. This leaves us y=f(u) and u=g(x). Differentiating said terms leaves us wit...

Answered by Sam V. Maths tutor
2480 Views

How do we factorise?

The general form of factorising is that if we have ab+ac, we can rewrite this as a(b+c). We multiply each statement inside the bracket by a. So we’re effectively ripping out common terms. We are dividing ...

Answered by Sam V. Maths tutor
2349 Views

Separate (9x^2 + 8x + 10)/(x^2 + 1)(x + 2) into partial fractions.

First, we find the form of the two fractions we're going to get. As one denominator has a power of 2, and the other a power of 1, our answer will be of the form: [(Ax+B)/(x2+1)] + [C/(x+2)]. If...

Answered by Laura U. Maths tutor
3679 Views

Emily bought 3 books and 2 apples, and she spent £19, while her brother, John, spent £15 on 1 book and 5 apples. What is the cost of one book and one apple?

First we assign, for example, that x = cost of 1 book, and y = cost of 1 apple. Then we make these into simultaneous equations, such as: 3x+2y=19 (eqn. 1) and x+5y=15 (eqn. 2). Now multiply eqn. 2 to get ...

Answered by Laura U. Maths tutor
2459 Views

Let f ( x ) = 15 /x and g ( x ) = 2 x − 5 Find fg(4), gf(-30) and give the expression for gf(x)

Key here is the order of operation.g(4) =2x4 - 5=8-5=3fg(4) = f(3)=15/3=5gf(-30)f(-30)=15/-30=-1/2gf(-30)=g(-1/2)=2x-1/2 -5=-1-5=-6gf(x)f(x)=15/xg(15/x)=2*15/x -5=30/x -5

Answered by Eddie M. Maths tutor
4568 Views

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