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3/5 of a number is 162. Work out what 4/5 of the same number is.

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Expand the brackets? (x+4)(2x-3)

Create a smiling face with arrows between the terms and then go through and multiply the terms together.(Diagram of the smiling face)(x+4)(2x-3) = 2x 2 - 12 - 3x + 8x = 2x 2 + 5x - 12Then simply reorganise t...
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Answered by Tim R. • Maths tutor
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Solve: 3x+5y=19 4x-2y=-18

These are simultaneous equations and we need to find the value of X and Y. We can use the elimination method. The coefficients (the amount the letter is being multiplied by) of X and Y do not match. First, w...
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Answered by Charlotte L. • Maths tutor
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How do I maximise/minimise a given function f(x)?

To find an extreme point of a function you must first take the derivative of f(x) with respect to x. As the function will peak/trough at the extreme point, the gradient at this point will be equal to 0 and t...
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The curve C has the equation y=3x/(9+x^2 ) (a) Find the turning points of the curve C (b) Using the fact that (d^2 y)/(dx^2 )=(6x(x^2-27))/(x^2+9)^3 or otherwise, classify the nature of each turning point of C

(a)To find the turning points of a curve, need to solve dy/dx=0. Using the quotient rule one can differentiate y:y=f(x)/g(x) dy/dx=(f'(x)g(x)-f(x)g'(x))/(g(x)) 2 f(x)=3x, f'(x)=3, g(x)=(9+x 2 ), g'(x)=2x→ dy...
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Answered by Liora C. • Maths tutor
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