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  1. Sketch, on the same set of axes, the curves

    y=2|ln⁡(x)|

    and

    y=ln⁡(x+1)
  2. Find the value of x>1 for which these curves intersect.

  3. By considering the other point of intersection, show that the cubic equation

    x3+x2−1=0

    has a real root between 0 and 1 (you do not need to calculate this root).


For (a), remember that x↦ln⁡(x) is the inverse function of x↦ex. To sketch an inverse function you need reflect in the line y=x.

Now, to get y=ln⁡(x+1), consider this as a transformation of the curve y=ln⁡(x).


The answer to (b) can be expressed in the form

a+bc

where a,b,c are coprime. Give the value of

a+b+c