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  1. J

    More Maxima/Minima Problems

    How should we work out these questions? Q 16 A half-pipe is to be made from a rectangular piece of metal of length x meters. The perimeter of the rectangle is 30 meters. (a) Find the derivatives of the rectangle that will give the maximum surface area, correct to 1 decimal place. [Answer...
  2. J

    Maximum / Minima Problems

    6. Find two numbers whose sum is 28 and whose product is a maximum. 8. A piece of wire 10m long is broken into two parts, which are bent into the shape of a rectangle and a square. Find the dimensions x and y that make the total area a maximum. (x = width of rectangle, y = length of rectangle...
  3. J

    How do I get the exact gradient, with rational denominator, of the normal of parabola

    Hi. So, I need to get the exact gradient of the normal of the parabola y^2=12x at the point where x=4 in the first quadrant. I get near the answer which is -(2√3)/3 but I couldn't get the working right. Any help is very much appreciated. Thank you.
  4. J

    (HELP!) Can you please help me find the equation of this parabola? (concave down)

    Question 7 of Challenge 10 Maths in Focus (Preliminary Course) Find the equation of the parabola with axis parallel to the y-axis and passing through points (0,-2), (1,0) and (3, -8). I don't know how to do this problem, can anyone please show me working onto solving this? Thank you very...
  5. J

    Can anyone solve these locus problems?

    Can anyone please help me solve these problems? 1. Find the equation of the locus of a point that moves so that it is equidistant from the line 4x-3y+2=0 and the line 3x+4y-7=0. 2. Given two points A(3, -2) and B(-1, 7), find the equation of the locus of P(x, y) if the gradient of PA is twice...
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