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Solve the equation $x^2 - x - 6 = 0.$ The graphs of four quadratic functions are shown below - Leaving Cert Mathematics - Question (a)(b)(c) - 2014

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Question (a)(b)(c)

Solve-the-equation--$x^2---x---6-=-0.$--The-graphs-of-four-quadratic-functions-are-shown-below-Leaving Cert Mathematics-Question (a)(b)(c)-2014.png

Solve the equation $x^2 - x - 6 = 0.$ The graphs of four quadratic functions are shown below. Graph A Graph B Graph C Graph D Which of the graphs above is t... show full transcript

Worked Solution & Example Answer:Solve the equation $x^2 - x - 6 = 0.$ The graphs of four quadratic functions are shown below - Leaving Cert Mathematics - Question (a)(b)(c) - 2014

Step 1

Solve the equation $x^2 - x - 6 = 0$

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Answer

To solve the equation x2x6=0x^2 - x - 6 = 0, we can factor it:

(x+2)(x3)=0(x + 2)(x - 3) = 0 This gives us two solutions:

  1. x+2=0    x=2x + 2 = 0 \implies x = -2
  2. x3=0    x=3x - 3 = 0 \implies x = 3

Therefore, the solutions are x=2x = -2 and x=3.x = 3.

Step 2

Which of the graphs above is that of the function $f: x \to x^2 - x - 6$?

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The correct graph for the function f(x)=x2x6f(x) = x^2 - x - 6 can be identified by finding the vertex and the intercepts. The vertex lies at x=b2a=12x = \frac{-b}{2a} = \frac{1}{2}. The function opens upwards, and the curve intersects the x-axis at x=2x = -2 and x=3x = 3. Upon examining the provided graphs,

Graph D accurately depicts these features.

Step 3

(i) $h(x) = g(x) + 2$

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To sketch h(x)h(x), we take the graph of g(x)g(x) and shift it up by 2 units. Therefore, the entire graph of g(x)g(x) will be displaced vertically upwards. This includes moving the vertex from (1, 1) to (1, 3). The new points after the upward shift will represent the graph of h(x)h(x).

Step 4

(ii) $k(x) = g(x + 2)$

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To sketch k(x)k(x), we need to shift the graph of g(x)g(x) horizontally to the left by 2 units. This means if the original vertex of g(x)g(x) is at (1, 1), the vertex of k(x)k(x) will now be at (-1, 1). Plot the new vertex and ensure that the shape of the parabola remains consistent while adjusting the x-coordinates accordingly.

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