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a) You area told that y is proportional to x2 and that when y = 75, x = 5. Find a formula for y in terms of x. y = x b) Find the value of y when x = 3. c) Find the value of x when y = 1200.

a) y is proportional to x^2, when x is 5, y is 75 Therefore: 75 = (something multiplied by) 5^2 75 = 3 x 25 Hence y = 3x^2 b) y = 3 multiplied by 3^2 = 27 c) 1200 = 3x^2 1200/3 = x^2 400 = x^2 Undo the squar...
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Answered by Kezia M. • Maths tutor
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Dipen and Nisha are planning their wedding reception. Nisha says, “I want to invite 70 guests.” Dipen says, “If we invite one-fifth fewer guests, we will save more than £500” Is Dipen correct? (Taken from Nov 2014 AQA Unit 2)

Need to calculate two things in order to answer the question: 1) Total cost of Nisha's 70 guests. 2) Total cost of Dipen's 'one-fifth fewer' guests. For Nishen: Total cost = £40 * 70 minus the 5% reduction =...
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Answered by Alex N. • Maths tutor
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What's the difference between the mean, median and mode?

The mean, median and mode are three types of averages which you will be asked about in your GCSE maths exam. The best way to learn maths is by by doing it or at least running through examples. E.g. Given the...
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Answered by Thomas K. • Maths tutor
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How do I factorise a quadratic equation?

Firstly , make sure you agree that a quadratic equation is an equation of the form y = ax 2 + bx + c where a , b , c are (real) constants ( a is not 0), and x is the variable. (Note: the equation has an &quo...
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Answered by Gemma L. • Maths tutor
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differentiate x^3(1+x)^5 with respect for x

First we have to use the product rule, remember that if we have h(x)=f(x)g(x) then h'(x)=f'(x)g(x)+f(x)g'(x).So h'(x) = x^3D[(x+1)^5]+(x+1)^5D[x^3]Completing the unfinished derivatives,h'(x) = x^3[5(x+1)^4]+...
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Answered by Robert L. • Maths tutor
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