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Maths
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When do I use the chain rule and when do I use the product rule in differentiation?

These are two really useful rules for differentiating functions. We use the chain rule when differentiating a 'function of a function', like f(g(x)) in general. We use the product rule when differentiatin...

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Answered by Michael O. Maths tutor
164034 Views

Express 6cos(2x) + sin(x) in terms of sin(x), hence solve the equation 6cos(2x) + sin(x) = 0 for 0<x<360

For the 1st part of the question: use the double angle formula to rewrite cos(2x) = cos^2(x) - sin^2(x). Then use the basic identity to write cos^2(x) = 1-sin^2(x), hence cos(2x) = 1-2sin^2(x). Plug the r...

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Answered by Gwen F. Maths tutor
9535 Views

If I buy a dress at 30% off the original price and I pay £40. How much was the dress originally?

I like to address this question by using similar fractions. That is to say x/y=2x/2y X over y is the same as 2x over 2y In this example we are asked what the full price of the dress is, as in what 100% of...

LR
Answered by Lauren R. Maths tutor
5263 Views

A right angled triangle with sides 7cm and 11cm, find the hypotenuse

General rule for any right angled triangle: a^2+b^2=c^2, with a and b being the shorter sides and c being the hypotenuse (the longest side). Using the equation: a=7 and b = 11 and c=hypotenuse we want to ...

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Answered by Gwen F. Maths tutor
4579 Views

Make x the subject of the equation y=(3x+5)/(4-x)

(1) Get rid of the fraction by multiply both sides by (4-x), we now have y(4-x)=3x+5. (2) Expand any brackets, so 4y-py=3x+5. (3) Rearrange to get all the x to one side: 4y-5=3x+px. (4) Factorise x becaus...

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Answered by Gwen F. Maths tutor
12435 Views

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