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A) Draw the graph for the relation y = x2 − 3x − 5 using the interval -3 x 6. From the graph, find the; (i) coordinates at the turning point. (ii) the minimum value (iii) the truthset of y = x2 − 3x -

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Here are the solutions for questions 8 and 9.

Question 8:

a) Draw the graph for the relation y=x2−3x−5y = x^2 - 3x - 5 using the interval −3≤x≤6-3 \le x \le 6. From the graph, find the;

(i) coordinates at the turning point.

(ii) the minimum value

(iii) the truthset of y=x2−3x−5=0y = x^2 - 3x - 5 = 0

b) Find the equation whose roots are -6 and 13.

  1. Create a table of values for y=x2−3x−5y = x^2 - 3x - 5 for xx from −3-3 to 6.

    x−3−2−10123456y135−1−5−7−7−5−1513\begin{array}{|c|c|c|c|c|c|c|c|c|c|c|} \hline x & -3 & -2 & -1 & 0 & 1 & 2 & 3 & 4 & 5 & 6 \\ \hline y & 13 & 5 & -1 & -5 & -7 & -7 & -5 & -1 & 5 & 13 \\ \hline \end{array}

    Note: The graph would be drawn by plotting these points and drawing a smooth curve through them.

  2. Find the coordinates of the turning point.

    The turning point (vertex) of a parabola y=ax2+bx+cy = ax^2 + bx + c is at x=−b2ax = \frac{-b}{2a}.
    For y=x2−3x−5y = x^2 - 3x - 5, we have a=1a=1, b=−3b=-3, c=−5c=-5.

    x=−(−3)2(1)=32=1.5x = \frac{-(-3)}{2(1)} = \frac{3}{2} = 1.5

    Substitute x=1.5x=1.5 into the equation to find yy:

    y=(1.5)2−3(1.5)−5=2.25−4.5−5=−7.25y = (1.5)^2 - 3(1.5) - 5 = 2.25 - 4.5 - 5 = -7.25

    (i) The coordinates at the turning point (read from the graph) are approximately (1.5,−7.25)\boxed{(1.5, -7.25)}.

  3. Find the minimum value.

    (ii) The minimum value (read from the graph) is the yy-coordinate of the turning point: −7.25\boxed{-7.25}.

  4. Find the truthset of y=x2−3x−5=0y = x^2 - 3x - 5 = 0.

    The truthset consists of the xx-intercepts where y=0y=0. From the table, yy changes from negative to positive between x=−1x=-1 and x=0x=0, and between x=4x=4 and x=5x=5.
    Using the quadratic formula x=−b±b2−4ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}:

    x=−(−3)±(−3)2−4(1)(−5)2(1)x = \frac{-(-3) \pm \sqrt{(-3)^2 - 4(1)(-5)}}{2(1)} x=3±9+202x = \frac{3 \pm \sqrt{9 + 20}}{2} x=3±292x = \frac{3 \pm \sqrt{29}}{2} x1=3−292≈3−5.3852≈−1.19x_1 = \frac{3 - \sqrt{29}}{2} \approx \frac{3 - 5.385}{2} \approx -1.19 x2=3+292≈3+5.3852≈4.19x_2 = \frac{3 + \sqrt{29}}{2} \approx \frac{3 + 5.385}{2} \approx 4.19

    (iii) The truthset of y=x2−3x−5=0y = x^2 - 3x - 5 = 0 (read from the graph) is approximately {−1.19,4.19}\boxed{\{-1.19, 4.19\}}.

    Part 8b:

  5. Find the equation whose roots are −6-6 and 13.

    If the roots are α\alpha and β\beta, the quadratic equation is x2−(α+β)x+αβ=0x^2 - (\alpha + \beta)x + \alpha\beta = 0.
    Given roots α=−6\alpha = -6 and β=13\beta = 13.
    Sum of roots: α+β=−6+13=7\alpha + \beta = -6 + 13 = 7.
    Product of roots: αβ=(−6)(13)=−78\alpha\beta = (-6)(13) = -78.
    Substitute these values into the general equation:

    x2−(7)x+(−78)=0x^2 - (7)x + (-78) = 0

    The equation is x2−7x−78=0\boxed{x^2 - 7x - 78 = 0}.

    Question 9:
    A total of 50 items consisting of pens and pencils were bought for GH¢190. A pen cost GH¢ and a pencil costs GH¢3.
    a. form a linear equation to represent the situation
    b. find the number of pen and pencils bought
    c. how much will a customer pay for 8 pens and 4 pencils.

    Assumption: The cost of a pen is missing from the question. We will assume the cost of a pen is GH¢4.

  6. Define variables and form linear equations.

    Let pp be the number of pens and cc be the number of pencils.
    The total number of items is 50:

    p+c=50(1)p + c = 50 \quad (1)

    The cost of a pen is GH¢4 and a pencil is GH¢3. The total cost is GH¢190:

    4p+3c=190(2)4p + 3c = 190 \quad (2)

    a) The linear equations representing the situation are:
    p+c=50\boxed{p + c = 50}
    4p+3c=190\boxed{4p + 3c = 190}

  7. Solve the system of equations to find the number of pens and pencils.

    From equation (1), express cc in terms of pp:

    c=50−pc = 50 - p

    Substitute this into equation (2):

    4p+3(50−p)=1904p + 3(50 - p) = 190 4p+150−3p=1904p + 150 - 3p = 190 p+150=190p + 150 = 190 p=190−150p = 190 - 150 p=40p = 40

    Now find cc:

    c=50−40=10c = 50 - 40 = 10

    b) The number of pens bought is 40\boxed{40} and the number of pencils bought is 10\boxed{10}.

  8. Calculate the cost for 8 pens and 4 pencils.

    Cost of 8 pens = 8×GH¢4=GH¢328 \times \text{GH¢}4 = \text{GH¢}32.
    Cost of 4 pencils = 4×GH¢3=GH¢124 \times \text{GH¢}3 = \text{GH¢}12.
    Total cost = Cost of 8 pens +

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