Known polynomial, verify then factorise

Questions where the polynomial is completely specified and students must verify the given factor using the factor theorem, then factorise completely.

15 questions

Edexcel C2 2008 June Q1
1. $$f ( x ) = 2 x ^ { 3 } - 3 x ^ { 2 } - 39 x + 20$$
  1. Use the factor theorem to show that \(( x + 4 )\) is a factor of \(\mathrm { f } ( x )\).
  2. Factorise f ( \(x\) ) completely.
Edexcel C2 2012 June Q4
4. $$f ( x ) = 2 x ^ { 3 } - 7 x ^ { 2 } - 10 x + 24$$
  1. Use the factor theorem to show that \(( x + 2 )\) is a factor of \(\mathrm { f } ( x )\).
  2. Factorise f(x) completely.
Edexcel C2 2014 June Q2
2. $$f ( x ) = 2 x ^ { 3 } - 7 x ^ { 2 } + 4 x + 4$$
  1. Use the factor theorem to show that \(( x - 2 )\) is a factor of \(\mathrm { f } ( x )\).
  2. Factorise \(\mathrm { f } ( x )\) completely.
Edexcel C2 2005 June Q3
  1. Use the factor theorem to show that \(( x + 4 )\) is a factor of \(2 x ^ { 3 } + x ^ { 2 } - 25 x + 12\).
  2. Factorise \(2 x ^ { 3 } + x ^ { 2 } - 25 x + 12\) completely.
OCR C2 2011 January Q9
9
\includegraphics[max width=\textwidth, alt={}, center]{c52fe7e9-0442-4b3e-b924-2e5e4b3e98f5-04_584_785_255_680} The diagram shows the curve \(y = \mathrm { f } ( x )\), where \(\mathrm { f } ( x ) = - 4 x ^ { 3 } + 9 x ^ { 2 } + 10 x - 3\).
  1. Verify that the curve crosses the \(x\)-axis at ( 3,0 ) and hence state a factor of \(\mathrm { f } ( x )\).
  2. Express \(\mathrm { f } ( x )\) as the product of a linear factor and a quadratic factor.
  3. Hence find the other two points of intersection of the curve with the \(x\)-axis.
  4. The region enclosed by the curve and the \(x\)-axis is shaded in the diagram. Use integration to find the total area of this region.
OCR MEI AS Paper 1 2019 June Q7
7 In this question you must show detailed reasoning.
  1. Nigel is asked to determine whether \(( x + 7 )\) is a factor of \(x ^ { 3 } - 37 x + 84\). He substitutes \(x = 7\) and calculates \(7 ^ { 3 } - 37 \times 7 + 84\). This comes to 168 , so Nigel concludes that ( \(x + 7\) ) is not a factor. Nigel's conclusion is wrong.
    • Explain why Nigel's argument is not valid.
    • Show that \(( x + 7 )\) is a factor of \(x ^ { 3 } - 37 x + 84\).
    • Sketch the graph of \(y = x ^ { 3 } - 37 x + 84\), indicating the coordinates of the points at which the curve crosses the coordinate axes.
    • The graph in part (b) is translated by \(\binom { 1 } { 0 }\). Find the equation of the translated graph, giving your answer in the form \(y = x ^ { 3 } + a x ^ { 2 } + b x + c\) where \(a , b\) and \(c\) are integers.
OCR MEI AS Paper 2 2023 June Q7
7
  1. Use the factor theorem to show that \(( x - 2 )\) is a factor of \(x ^ { 3 } + 6 x ^ { 2 } - x - 30\).
  2. Factorise \(x ^ { 3 } + 6 x ^ { 2 } - x - 30\) completely.
AQA C1 2010 January Q1
1 The polynomial \(\mathrm { p } ( x )\) is given by \(\mathrm { p } ( x ) = x ^ { 3 } - 13 x - 12\).
  1. Use the Factor Theorem to show that \(x + 3\) is a factor of \(\mathrm { p } ( x )\).
  2. Express \(\mathrm { p } ( x )\) as the product of three linear factors.
AQA C1 2006 June Q6
6 The polynomial \(\mathrm { p } ( x )\) is given by \(\mathrm { p } ( x ) = x ^ { 3 } - 4 x ^ { 2 } + 3 x\).
  1. Use the Factor Theorem to show that \(x - 3\) is a factor of \(\mathrm { p } ( x )\).
  2. Express \(\mathrm { p } ( x )\) as the product of three linear factors.
    1. Use the Remainder Theorem to find the remainder, \(r\), when \(\mathrm { p } ( x )\) is divided by \(x - 2\).
    2. Using algebraic division, or otherwise, express \(\mathrm { p } ( x )\) in the form $$( x - 2 ) \left( x ^ { 2 } + a x + b \right) + r$$ where \(a , b\) and \(r\) are constants.
AQA C1 2012 June Q3
3 The polynomial \(\mathrm { p } ( x )\) is given by $$\mathrm { p } ( x ) = x ^ { 3 } + 2 x ^ { 2 } - 5 x - 6$$
    1. Use the Factor Theorem to show that \(x + 1\) is a factor of \(\mathrm { p } ( x )\).
    2. Express \(\mathrm { p } ( x )\) as the product of three linear factors.
  1. Verify that \(\mathrm { p } ( 0 ) > \mathrm { p } ( 1 )\).
  2. Sketch the curve with equation \(y = x ^ { 3 } + 2 x ^ { 2 } - 5 x - 6\), indicating the values where the curve crosses the \(x\)-axis.
Edexcel C2 Q1
  1. (a) Using the factor theorem, show that \(( x + 3 )\) is a factor of
$$x ^ { 3 } - 3 x ^ { 2 } - 10 x + 24$$ (b) Factorise \(x ^ { 3 } - 3 x ^ { 2 } - 10 x + 24\) completely.
Edexcel C2 Q7
7
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  1. (a) Using the factor theorem, show that \(( x + 3 )\) is a factor of
$$x ^ { 3 } - 3 x ^ { 2 } - 10 x + 24$$ (b) Factorise \(x ^ { 3 } - 3 x ^ { 2 } - 10 x + 24\) completely.
2. $$f ( n ) = n ^ { 3 } + p n ^ { 2 } + 11 n + 9 , \text { where } p \text { is a constant. }$$ (a) Given that \(\mathrm { f } ( n )\) has a remainder of 3 when it is divided by ( \(n + 2\) ), prove that \(p = 6\).
(b) Show that \(\mathrm { f } ( n )\) can be written in the form \(( n + 2 ) ( n + q ) ( n + r ) + 3\), where \(q\) and \(r\) are integers to be found.
(c) Hence show that \(\mathrm { f } ( n )\) is divisible by 3 for all positive integer values of \(n\).
3. Find the values of \(\theta\), to 1 decimal place, in the interval \(- 180 \leq \theta < 180\) for which $$2 \sin ^ { 2 } \theta ^ { \circ } - 2 \sin \theta ^ { \circ } = \cos ^ { 2 } \theta ^ { \circ } .$$
  1. Every \(\pounds 1\) of money invested in a savings scheme continuously gains interest at a rate of \(4 \%\) per year. Hence, after \(x\) years, the total value of an initial \(\pounds 1\) investment is \(\pounds y\), where
$$y = 1.04 ^ { x }$$ (a) Sketch the graph of \(y = 1.04 ^ { x } , x \geq 0\).
(b) Calculate, to the nearest \(\pounds\), the total value of an initial \(\pounds 800\) investment after 10 years.
(c) Use logarithms to find the number of years it takes to double the total value of any initial investment.
5. The curve \(C\) with equation \(y = p + q e ^ { x }\), where \(p\) and \(q\) are constants, passes through the point \(( 0,2 )\). At the point \(P ( \ln 2 , p + 2 q\) on \(C\), the gradient is 5 .
(a) Find the value of p and the value of \(q\). The normal to \(C\) at \(P\) crosses the \(x\)-axis at \(L\) and the \(y\)-axis at \(M\).
(b) Show that the area of \(\triangle O L M\), where \(O\) is the origin, is approximately 53.8
6. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 3} \includegraphics[alt={},max width=\textwidth]{04f9d12c-3423-441a-b1ff-fe39ef6e51ed-3_517_1300_760_370}
\end{figure} Figure 3 shows part of the curve \(C\) with equation $$y = \frac { 3 } { 2 } x ^ { 2 } - \frac { 1 } { 4 } x ^ { 3 } .$$ The curve \(C\) touches the \(x\)-axis at the origin and passes through the point \(A ( p , 0 )\).
(a) Show that \(p = 6\).
(b) Find an equation of the tangent to \(C\) at \(A\). The curve \(C\) has a maximum at the point \(P\).
(c) Find the \(x\)-coordinate of \(P\). The shaded region \(R\), in Fig. 3, is bounded by \(C\) and the \(x\)-axis.
(d) Find the area of \(R\).
7. Figure 1 \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{04f9d12c-3423-441a-b1ff-fe39ef6e51ed-4_499_492_319_420} \captionsetup{labelformat=empty} \caption{Shape X}
\end{figure} \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{04f9d12c-3423-441a-b1ff-fe39ef6e51ed-4_597_474_274_1096} \captionsetup{labelformat=empty} \caption{Shape \(Y\)}
\end{figure} Figure 1 shows the cross-sections of two drawer handles. Shape \(X\) is a rectangle \(A B C D\) joined to a semicircle with \(B C\) as diameter. The length \(A B = d \mathrm {~cm}\) and \(B C = 2 d \mathrm {~cm}\). Shape \(Y\) is a sector \(O P Q\) of a circle with centre \(O\) and radius \(2 d \mathrm {~cm}\).
Angle \(P O Q\) is \(\theta\) radians.
Given that the areas of the shapes \(X\) and \(Y\) are equal,
(a) prove that \(\theta = 1 + \frac { 1 } { 4 } \pi\). Using this value of \(\theta\), and given that \(d = 3\), find in terms of \(\pi\),
(b) the perimeter of shape \(X\),
(c) the perimeter of shape \(Y\).
(d) Hence find the difference, in mm, between the perimeters of shapes \(X\) and \(Y\).
Edexcel C2 Q1
\begin{enumerate} \item (a) Using the factor theorem, show that \(( x + 3 )\) is a factor of \(x ^ { 3 } - 3 x ^ { 2 } - 10 x + 24\).
(b) Factorise \(x ^ { 3 } - 3 x ^ { 2 } - 10 x + 24\) completely. \item (a) Expand \(( 2 \sqrt { } x + 3 ) ^ { 2 }\).
(b) Hence evaluate \(\int _ { 1 } ^ { 2 } ( 2 \sqrt { } x + 3 ) ^ { 2 } \mathrm {~d} x\), giving your answer in the form \(a + b \sqrt { } 2\), where \(a\) and \(b\) are integers. \item The first three terms in the expansion, in ascending powers of \(x\), of \(( 1 + p x ) ^ { n }\), are \(1 - 18 x + 36 p ^ { 2 } x ^ { 2 }\). Given that \(n\) is a positive integer, find the value of \(n\) and the value of \(p\).
[0pt] [P2 January 2003 Question 2] \item A circle \(C\) has equation \(x ^ { 2 } + y ^ { 2 } - 6 x + 8 y - 75 = 0\).
Edexcel C2 Q1
\begin{enumerate} \item (a) Show that \(( x + 2 )\) is a factor of \(\mathrm { f } ( x ) = x ^ { 3 } - 19 x - 30\).
(b) Factorise \(\mathrm { f } ( x )\) completely. \item For the binomial expansion, in descending powers of \(x\), of \(\left( x ^ { 3 } - \frac { 1 } { 2 x } \right) ^ { 12 }\),
SPS SPS SM 2021 November Q5
5 marks
5.
\(\mathrm { p } ( x ) = 30 x ^ { 3 } - 7 x ^ { 2 } - 7 x + 2\)
Prove that ( \(2 x + 1\) ) is a factor of \(\mathrm { p } ( x )\)
[0pt] [2 marks]
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L Factorise \(\mathrm { p } ( x )\) completely.
[0pt] [3 marks]
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