CAIE P1 (Pure Mathematics 1) 2020 March

1 The function f is defined by \(\mathrm { f } ( x ) = \frac { 1 } { 3 x + 2 } + x ^ { 2 }\) for \(x < - 1\).
Determine whether f is an increasing function, a decreasing function or neither.

2 The graph of \(y = \mathrm { f } ( x )\) is transformed to the graph of \(y = 1 + \mathrm { f } \left( \frac { 1 } { 2 } x \right)\).
Describe fully the two single transformations which have been combined to give the resulting transformation.

3
\includegraphics[max width=\textwidth, alt={}, center]{01b98496-a717-4c68-8489-42d2203b700f-04_700_401_260_870} The diagram shows part of the curve with equation \(y = x ^ { 2 } + 1\). The shaded region enclosed by the curve, the \(y\)-axis and the line \(y = 5\) is rotated through \(360 ^ { \circ }\) about the \(\boldsymbol { y }\)-axis. Find the volume obtained.

4 A curve has equation \(y = x ^ { 2 } - 2 x - 3\). A point is moving along the curve in such a way that at \(P\) the \(y\)-coordinate is increasing at 4 units per second and the \(x\)-coordinate is increasing at 6 units per second. Find the \(x\)-coordinate of \(P\).

5 Solve the equation $$\frac { \tan \theta + 3 \sin \theta + 2 } { \tan \theta - 3 \sin \theta + 1 } = 2$$ for \(0 ^ { \circ } \leqslant \theta \leqslant 90 ^ { \circ }\).

6 The coefficient of \(\frac { 1 } { x }\) in the expansion of \(\left( 2 x + \frac { a } { x ^ { 2 } } \right) ^ { 5 }\) is 720 .

1. Find the possible values of the constant \(a\).
2. Hence find the coefficient of \(\frac { 1 } { x ^ { 7 } }\) in the expansion.

7
\includegraphics[max width=\textwidth, alt={}, center]{01b98496-a717-4c68-8489-42d2203b700f-08_574_689_260_726} The diagram shows a sector \(A O B\) which is part of a circle with centre \(O\) and radius 6 cm and with angle \(A O B = 0.8\) radians. The point \(C\) on \(O B\) is such that \(A C\) is perpendicular to \(O B\). The arc \(C D\) is part of a circle with centre \(O\), where \(D\) lies on \(O A\). Find the area of the shaded region.

8 A woman's basic salary for her first year with a particular company is \(
) 30000\( and at the end of the year she also gets a bonus of \)\\( 600\).

1. For her first year, express her bonus as a percentage of her basic salary.
   At the end of each complete year, the woman's basic salary will increase by \(3 \%\) and her bonus will increase by \(
   ) 100$.
2. Express the bonus she will be paid at the end of her 24th year as a percentage of the basic salary paid during that year.

9

1. Express \(2 x ^ { 2 } + 12 x + 11\) in the form \(2 ( x + a ) ^ { 2 } + b\), where \(a\) and \(b\) are constants.
   The function f is defined by \(\mathrm { f } ( x ) = 2 x ^ { 2 } + 12 x + 11\) for \(x \leqslant - 4\).
2. Find an expression for \(\mathrm { f } ^ { - 1 } ( x )\) and state the domain of \(\mathrm { f } ^ { - 1 }\).
   The function g is defined by \(\mathrm { g } ( x ) = 2 x - 3\) for \(x \leqslant k\).
3. For the case where \(k = - 1\), solve the equation \(\operatorname { fg } ( x ) = 193\).
4. State the largest value of \(k\) possible for the composition fg to be defined.

10 The gradient of a curve at the point \(( x , y )\) is given by \(\frac { \mathrm { d } y } { \mathrm {~d} x } = 2 ( x + 3 ) ^ { \frac { 1 } { 2 } } - x\). The curve has a stationary point at \(( a , 14 )\), where \(a\) is a positive constant.

1. Find the value of \(a\).
2. Determine the nature of the stationary point.
3. Find the equation of the curve.

11

1. Solve the equation \(3 \tan ^ { 2 } x - 5 \tan x - 2 = 0\) for \(0 ^ { \circ } \leqslant x \leqslant 180 ^ { \circ }\).
2. Find the set of values of \(k\) for which the equation \(3 \tan ^ { 2 } x - 5 \tan x + k = 0\) has no solutions.
3. For the equation \(3 \tan ^ { 2 } x - 5 \tan x + k = 0\), state the value of \(k\) for which there are three solutions in the interval \(0 ^ { \circ } \leqslant x \leqslant 180 ^ { \circ }\), and find these solutions.

12 A diameter of a circle \(C _ { 1 }\) has end-points at \(( - 3 , - 5 )\) and \(( 7,3 )\).

1. Find an equation of the circle \(C _ { 1 }\).
   \includegraphics[max width=\textwidth, alt={}, center]{01b98496-a717-4c68-8489-42d2203b700f-16_618_846_1062_644} The circle \(C _ { 1 }\) is translated by \(\binom { 8 } { 4 }\) to give circle \(C _ { 2 }\), as shown in the diagram.
2. Find an equation of the circle \(C _ { 2 }\).
   The two circles intersect at points \(R\) and \(S\).
3. Show that the equation of the line \(R S\) is \(y = - 2 x + 13\).
4. Hence show that the \(x\)-coordinates of \(R\) and \(S\) satisfy the equation \(5 x ^ { 2 } - 60 x + 159 = 0\).
   If you use the following lined page to complete the answer(s) to any question(s), the question number(s) must be clearly shown.