[discia] GCSE Maths › Algebra › Drawing Other Graphs: Cubic/Reciprocal

Drawing Other Graphs: Cubic/Reciprocal

discia.org 10 questions · 28 marks
Name Date
  1. Either paper 3 marks
    The table shows some values of \(y = x^3 - 3x + 4\)
    x-3-2-10123
    y-14646
    Three of the \(y\) values are missing.
    (a)

    Work out the value of \(y\) when \(x = -2\).

    (b)

    Work out the value of \(y\) when \(x = 1\).

    (c)

    Work out the value of \(y\) when \(x = 3\).

    Show answer
    (a) \(2\)
    (b) \(2\)
    (c) \(22\)
    Another like this
  2. Either paper 3 marks

    The graph of \(y = -x^3 + 4x^2 +x - 4\) is drawn on the grid.

    On the \(x\)-axis each square is \(1\). On the \(y\)-axis the numbered lines are \(5\) apart, and the fainter lines between them are \(1\) apart.

    xy-2-112345-30-25-20-15-10-551015200

    Use the graph to write down the three solutions of \(-x^3 + 4x^2 +x - 4 = 0\)

    Show answer
    \(x = -1\), \(x = 1\) and \(x = 4\)
    Another like this
  3. Either paper 2 marks

    The graph of \(y = \frac{ 8 }{ x }\) is drawn on the grid. Each square is \(1\).

    The graph is in two separate pieces, one in each of two opposite corners.

    xy-9-8-7-6-5-4-3-2123456789-9-8-7-6-5-4-3-21234567890
    (a)

    Use the graph to write down the value of \(y\) when \(x = 2\).

    (b)

    Use the graph to write down the value of \(x\) when \(y = 1\).

    Show answer
    (a) \(4\)
    (b) \(8\)
    Another like this
  4. Either paper 3 marks

    The graph of \(y = \frac{ 6 }{ x }\) is drawn on the grid.

    xy-9-8-7-6-5-4-3-2123456789-9-8-7-6-5-4-3-21234567890

    Both branches bend towards the axes without ever arriving.

    (a)

    Calculate the value of \(y\) when \(x = 2000\).

    Give your answer as a decimal.

    (b)

    Explain why the graph never touches the \(x\)-axis.

    (c)

    Explain why the graph never touches the \(y\)-axis.

    Show answer
    (a) \(0.003\)
    (b) Because y is only 0 when the numerator is 0, and it never is — dividing a fixed number by x always leaves something, however large x gets.
    (c) Because a point on the y-axis has x = 0, and you cannot divide by 0, so there is no value of y there.
    Another like this
  5. Either paper 3 marks
    The table gives some values of \(y = \frac{ 38 }{ x }\)
    x-16-4-2-112416
    y-2.375-19-383819
    Three of the \(y\) values are missing. Give each of your answers as a decimal.
    (a)

    Work out the value of \(y\) when \(x = -4\).

    (b)

    Work out the value of \(y\) when \(x = 16\).

    (c)

    Work out the value of \(y\) when \(x = 4\).

    Show answer
    (a) \(-9.5\)
    (b) \(2.375\)
    (c) \(9.5\)
    Another like this
  6. Either paper 5 marks

    A curve has equation \(y = \frac{ a }{ x }\), where \(a\) is a number.

    The curve passes through the point \((2, 6)\).

    (a)

    Calculate the value of \(a\).

    (b)

    Calculate the value of \(y\) when \(x = 6\).

    (c)

    Calculate the value of \(x\) when \(y = -3\).

    Show answer
    (a) \(12\)
    (b) \(2\)
    (c) \(-4\)
    Another like this
  7. Either paper 3 marks
    A cyclist will travel 24 miles. Draw a graph to show the average speed of the cyclist for the five times taken in the table, 1, 2, 3, 4 and 6 hours. Plot only those five points on the grid. You may use the table to help you.
    time taken (hours)12346
    average speed (mph)124
    time taken (hours)average speed (mph)12345672468101214161820222426280
    Show answer
    A smooth curve through \((1, 24)\), \((2, 12)\), \((3, 8)\), \((4, 6)\) and \((6, 4)\), falling as the time increases
    time taken (hours)average speed (mph)12345672468101214161820222426280
    Another like this
  8. Either paper 4 marks
    Here is a table of values for \(y = 1 - x^3\) with some of the values missing.
    x-2-1012
    y20
    (a)

    Complete the table of values. Give the three missing values of \(y\) in the order they appear in the table.

    (b)

    On the grid, draw the graph of \(y = 1 - x^3\) for values of \(x\) from \(-2\) to \(2\).

    xy2-12-10-8-6-4-2246810120
    Show answer
    (a) \(9,\ 1,\ -7\)
    (b) A smooth curve through \((-2, 9)\), \((-1, 2)\), \((0, 1)\), \((1, 0)\) and \((2, -7)\)
    (b)xy2-12-10-8-6-4-2246810120
    Another like this
  9. Either paper 1 mark
    Here is a graph. xy-4-3-21234-6-5-4-3-2-11234560 Circle the letter of the equation of the graph.
    A\(y = 2 - x^3\)
    B\(y = \frac{ 1 }{ x } + 2\)
    C\(y = x^2 + 2\)
    D\(y = x^3 + 2\)
    Show answer
    C: \(y = x^2 + 2\)
    Another like this
  10. Either paper 1 mark

    \(y = \frac{ 8 }{ x }\)

    Which of these values of \(x\) gives the greatest value of \(y\)?

    Circle your answer.

    \(-78\) \qquad \(0.25\) \qquad \(54\) \qquad \(-0.32\)

    Show answer
    \(0.25\)
    Another like this
discia.org Drawing Other Graphs: Cubic/Reciprocal · sheet 1
Answers Drawing Other Graphs: Cubic/Reciprocal · sheet 1
  1. (a) \(2\)
    (b) \(2\)
    (c) \(22\)
  2. \(x = -1\), \(x = 1\) and \(x = 4\)
  3. (a) \(4\)
    (b) \(8\)
  4. (a) \(0.003\)
    (b) Because y is only 0 when the numerator is 0, and it never is — dividing a fixed number by x always leaves something, however large x gets.
    (c) Because a point on the y-axis has x = 0, and you cannot divide by 0, so there is no value of y there.
  5. (a) \(-9.5\)
    (b) \(2.375\)
    (c) \(9.5\)
  6. (a) \(12\)
    (b) \(2\)
    (c) \(-4\)
  7. A smooth curve through \((1, 24)\), \((2, 12)\), \((3, 8)\), \((4, 6)\) and \((6, 4)\), falling as the time increases
    time taken (hours)average speed (mph)12345672468101214161820222426280
  8. (a) \(9,\ 1,\ -7\)
    (b) A smooth curve through \((-2, 9)\), \((-1, 2)\), \((0, 1)\), \((1, 0)\) and \((2, -7)\)
    (b)xy2-12-10-8-6-4-2246810120
  9. C: \(y = x^2 + 2\)
  10. \(0.25\)
discia.org Drawing Other Graphs: Cubic/Reciprocal · sheet 1