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Topic 2 - Functions

Question 1

SLPaper 2

Let f(x)=x8f(x) = x - 8, g(x)=x43g(x) = x^4 - 3, and h(x)=f(g(x))h(x) = f(g(x)).

1.

Find h(x)h\left( x \right).

[2]
2.

Let CC be a point on the graph of hh. The tangent to the graph of hh at CC is parallel to the graph of ff. Find the xx-coordinate of CC.

[5]

Question 2

SLPaper 1

The function ff is defined for all xRx \in \mathbb{R}. The line with equation y=6x1y = 6x - 1 is the tangent to the graph of ff at x=4x = 4.

The function gg is defined for all xRx \in \mathbb{R} where g(x)=x23xg(x) = x^2 - 3x and h(x)=f(g(x))h(x) = f(g(x)).

1.

Write down the value of f(4){f}'(4).

[1]
2.

Find f(4)f(4).

[1]
3.

Find h(4)h(4).

[2]
4.

Hence find the equation of the tangent to the graph of hh at x=4x=4.

[3]

Question 3

SLPaper 2

SpeedWay airline flies from city AA to city BB. The flight time is normally distributed with a mean of 260 minutes and a standard deviation of 15 minutes. A flight is considered late if it takes longer than 275 minutes.

The flight is considered to be on time if it takes between mm and 275 minutes. The probability that a flight is on time is 0.830.

During a week, SpeedWay has 12 flights from city AA to city BB. The time taken for any flight is independent of the time taken by any other flight.

1.

Calculate the probability a flight is not late.

[2]
2.

Find the value of mm.

[3]
3.

Calculate the probability that at least 7{7} of these flights are on time.

[3]
4.

Given that at least 7{7} of these flights are on time, find the probability that exactly 10{10} flights are on time.

[4]
5.

SpeedWay increases the number of flights from city AA to city BB to 2020 flights each week, and improves their efficiency so that more flights are on time. The probability that at least 1919 flights are on time is 0.7880.788. A flight is chosen at random. Calculate the probability that it is on time.

[3]

Question 4

SLPaper 2

Let f(x)=xexf(x) = x \cdot e^{-x} and g(x)=3f(x)+1g(x) = -3f(x) + 1.

The graphs of ff and gg intersect at x=px = p and x=qx = q, where p<qp < q.

Question 5

SLPaper 1

The function ff is defined by f(x)=2x+43xf(x)=\frac{2x+4}{3-x}, where xRx \in \mathbb{R}, x3x \neq 3.

Write down the equation of

Find the coordinates where the graph of ff crosses

1.

the vertical asymptote of the graph of f{f}.

[1]
2.

the horizontal asymptote of the graph of ff.

[1]
3.

the xx-axis.

[1]
4.

the yy-axis.

[1]
5.

Sketch the graph of ff on the axes below. Graph

[1]

Question 6

SLPaper 1

A function ff is defined by f(x)=2x1x+1f(x) = \frac{2x-1}{x+1}, where xRx \in \mathbb{R}, x1x \neq -1.

The graph of y=f(x)y = f(x) has a vertical asymptote and a horizontal asymptote.

1.

Write down the equation of the vertical asymptote.

[1]
2.

Write down the equation of the horizontal asymptote.

[1]
3.

On the set of axes below, sketch the graph of y=f(x)y=f(x).

On your sketch, clearly indicate the asymptotes and the position of any points of intersection with the axes.

Graph

[3]
4.

Hence, solve the inequality 0<2x1x+1<2{0}<\frac{2x-1}{x+1}<2.

[1]

Question 7

HLPaper 1

The cubic equation x3kx2+3k=0x^3 - kx^2 + 3k = 0 where k>0k > 0 has roots α,β\alpha, \beta and α+β\alpha + \beta.

Given that αβ=k24\alpha \beta = -\frac{k^2}{4}, find the value of kk.

Question 8

SLPaper 1

The functions ff and gg are defined for xRx \in \mathbb{R} by f(x)=x2f(x) = x - 2 and g(x)=ax+bg(x) = ax + b, where a,bRa, b \in \mathbb{R}.

Given that fg(2)=3f \circ g(2) = -3 and gf(1)=5g \circ f(1) = 5, find the value of aa and the value of bb.

Question 9

SLPaper 2

The functions ff and gg are defined for xRx \in \mathbb{R} by f(x)=6x212x+1f(x) = 6x^2 - 12x + 1 and g(x)=x+cg(x) = -x + c, where cRc \in \mathbb{R}.

1.

Find the range of ff.

[2]
2.

Given that gf(x)0g \circ f(x) \leq 0 for all xRx \in \mathbb{R}, determine the set of possible values for cc.

[4]

Question 10

HLPaper 3

This question asks you to explore properties of a family of curves of the type y2=x3+ax+by^2 = x^3 + ax + b for various values of aa and bb, where a,bNa,b \in \mathbb{N}.

On the same set of axes, sketch the following curves for 2x2-2 \leq x \leq 2 and 2y2-2 \leq y \leq 2, clearly indicating any points of intersection with the coordinate axes.

Now, consider curves of the form y2=x3+by^2 = x^3 + b, for xb3x \geq -\sqrt[3]{b}, where bZ+b \in \mathbb{Z^+}.

Next, consider the curve y2=x3+xy^2 = x^3 + x, for x0x \geq 0.

The curve y2=x3+xy^2 = x^3 + x has two points of inflection. Due to the symmetry of the curve these points have the same xx-coordinate.

P(x,y)P(x,y) is defined to be a rational point on a curve if xx and yy are rational numbers. The tangent to the curve y2=x3+ax+by^2 = x^3 + ax + b at a rational point PP intersects the curve at another rational point QQ. Let CC be the curve y2=x3+2y^2 = x^3 + 2, for x23x \geq -\sqrt[3]{2}. The rational point P(1,1)P(-1,-1) lies on CC.

1.

y2=x3y^2=x^3, x0x \geq 0

[2]
2.

y2=x3+1{y^2 = x^3 + 1}, x1{x \geq -1}

[2]
3.

Write down the coordinates of the two points of inflexion on the curve y2=x3+1y^2=x^3+1

[1]
4.

By considering each curve from part (a), identify two key features that would distinguish one curve from the other.

[1]
5.

By varying the value of bb, suggest two key features common to these curves.

[2]
6.

Show that dydx=±3x2+12x3+x\frac{d y}{d x} = \pm \frac{3 x^2 + 1}{2\sqrt{x^3 + x}}, for x>0x > 0.

[3]
7.

Hence deduce that the curve y2=x3+xy^2=x^3+x has no local minimum or maximum points.

[1]
8.

Find the value of this xx-coordinate, giving your answer in the form x=p3+qrx = \sqrt{\frac{p\sqrt{3} + q}{r}}, where pp, qq, and rr are integers.

[7]
9.

Find the equation of the tangent to CC at PP.

[2]
10.

Hence, find the coordinates of the rational point QQ where this tangent intersects CC, expressing each coordinate as a fraction.

[2]
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