Quadratic Functions, Equations and Inequalities - Solving Quadratic Equations Graphically

Quadratic Functions, Equations and Inequalities - Solving Quadratic Equations Graphically

IP 2

Answer the whole of this question on a sheet of graph paper.

The table below gives some values of \(x\) and the corresponding values of \(y\) where\(y=-{{x}^{2}}+2x+5\) for \(-3\le x\le 5\).

\(x\)

\(-3\)

\(-2\)

\(-1\)

\(0\)

\(1\)

\(2\)

\(3\)

\(4\)

\(5\)

\(y\)

\(-10\)

\(-3\)

\(2\)

\(5\)

\(p\)

\(5\)

\(2\)

\(-3\)

\(-10\)

  1. Calculate the value of \(p\).
  2. Using a scale of 2 cm to represent 1 unit on the \(x\)-axis and 1 cm to represent 1 unit on the \(y\)-axis, draw the graph of \(y=-{{x}^{2}}+2x+5\).
  3. Use your graph to find the
    1. value of \(y\) when \(x=4.5\),
    2. maximum point.
  4. By drawing suitable line(s) to the graph, find the solution(s) to the equation
    1. \(-{{x}^{2}}+x+6=0\)
    2. \(-{{x}^{2}}+x+2=0\)

Solution:

Solution locked

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Answer:(a) \(p=6\) (b) Graph shown in working (c)(i) \(y\approx-6.3\) (ii) \((1,6)\) (d)(i) Draw \(y=x-1\): \(x=-2\) or \(3\) (ii) Draw \(y=x+3\): \(x=-1\) or \(2\)

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