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How do I construct a 'si' clause?

'Si' means 'if' in French. Like in English, it is used to talk about things that could happen . This is a 'si' clause in English: 'If I was rich, I would buy loads of books.' To say this in French, we would ...
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Answered by Elliot K. • French 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...
Answered by • Maths tutor
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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
5346 Views

Why do the trig addition formulae work?

Try differentiating:sin(x)cos(z-x)+cos(x)sin(z-x)with respect to x and for constant z, then simply the derivative you deduce, then integrate throughout the simplified equation. See what happens!
Answered by • Maths tutor
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