R3 FUNCTIONS AND GRAPHS V2020 - WordPress.com

102 SEKOLAH BUKIT SION - IGCSE MATH REVISION

MATHEMATICS (EXTENDED) 0580 IGCSE MAY/JUNE 2017

REVISION 3

FUNCTIONS AND GRAPHS


NOTES:


EXERCISE A 1.

The diagram shows the graph of y = !

"+ "

!,for 0 < x < 8.

(a) Use the graph to solve the equation !

"+ "

!= 3.

Answer: x = …………… or x = …………… [2]

(b) By drawing a suitable tangent, work out an estimate of the gradient of the graph where x = 1.

Answer: ………………………………………… [3]


2. (a) Find the co-ordinates of the midpoint of the line joining A(–8, 3) and B(–2, –3).

Answer: ( …………… , …………) [3]

(b) The line y = 4x + c passes through (2, 6). Find the value of c.

Answer: ………………………………………… [1]

(c) The lines 5x = 4y + 10 and 2y = kx – 4 are parallel.

Find the value of k.

Answer: ………………………………………… [2]


3. f(x) = (x + 2)3 – 5 g(x) = 2x + 10 h(x) = (

" , x ≠ 0.

Find

(a) gf(x)

Answer: ………………………………………… [2]

(b) f -1(x)

Answer: ………………………………………… [3]

(c) gh (− (+)

Answer: ………………………………………… [2]


4. The table shows some values for the equation y = x3 – 2x for –2 ≤ x ≤ 2.

(a) Complete the table of values. [3]

(b) On the grid below, draw the graph of y = x3 – 2x for –2 ≤ x ≤ 2. [4]


(c) (i) On the grid, draw the line y = 0.8 for –2 ≤ x ≤ 2. [1] (ii) Use your graph to solve for the equation x3 – 2x = 0.8.

Answer: x = …………… or x = …………… or x = …………… [3]

(d) By drawing a suitable tangent, work out an estimate for the gradient of the graph of y= x3 – 2x where x = –1.5. You must show your working.

Answer: ………………………………………… [3] 5. Find the equation of the line passing through the points (0, -1) and (3, 5).

Answer: ………………………………………… [3]


6. f(x) = 3x + 5 g(x) = 7 – 2x h(x) = x2 – 8 Find

(a) (i) f(3)

Answer: ………………………………………… [1] (ii) g(x – 3) in terms of x in its simplest form

Answer: ………………………………………… [2]

(iii) h(5x) in terms of x in its simplest form

Answer: ………………………………………… [1]

(b) Find the inverse function g -1(x).

Answer: ………………………………………… [2]

(c) Find hf(x) in the form of ax2 + bx + c.

Answer: ………………………………………… [3]

(d) Solve the equation ff(x) = 83.

Answer: ………………………………………… [3]

(e) Solve the inequality 2f(x) < g(x).

Answer: ………………………………………… [3]


7. f(x) = 2x

(a) Complete the table. [3]

(b) Draw the graph of y = f(x) for 0 ≤ x ≤ 4. [4]

(c) Use your graph in part (b) to solve the equation 2x = 5.

Answer: ………………………………………… [1]


(d) Draw a suitable straight line and use it to solve the equation 2x = 3x.

Answer: x =…………… or x = ……………… [3]

(e) Draw a suitable tangent and use it to find the co-ordinates of the point on the graph of y = f(x) where the gradient of the graph is 3.

Answer: ( …………… , …………) [3]

8. f(x) = 1 – 2x g(x) = (

" , x ≠ 0 h(x) = x3 + 1

(a) Find the value of

(i) gf(2)

Answer: ………………………………………… [2] (ii) h(–2)

Answer: ………………………………………… [1]

(b) Find fg(x). Write your answer as a single fraction.

Answer: ………………………………………… [2]

(c) Find h -1(x), the inverse of h(x).

Answer: ………………………………………… [2]


(d) Write down which of these sketches shows the graph of each of y = f(x), y = g(x) and y = h(x).

Answer: y = f(x) Graph …………… y = g(x) Graph …………… y = h(x) Graph …………… [3]

(e) k(x) = x5 – 3 Solve the equation k -1(x) = 2.

Answer: ………………………………………… [2]


9. f(x) = 5x + 4 g(x) = (!"

, x ≠ 0 h(x) = -(!."

Find

(a) fg(5),

Answer: ………………………………………… [2]

(b) gg(x) in its simplest form,

Answer: ………………………………………… [2]

(c) f -1(x)

Answer: ………………………………………… [2]

(d) the value of x when h(x) = 8.

Answer: ………………………………………… [2] 10. f(x) = x + !

" – 3, x ≠ 0 g(x) = "

!− 5

Find

(a) fg(18)

Answer: ………………………………………… [2]

(b) g-1(x)

Answer: ………………………………………… [2]


11. f(x) = 3 – x – x2 g(x) = 3x

(a) Complete the tables of values for f(x) and g(x). [2]

(b) On the grid, draw the graphs of y = f(x) and g(x) for – 1.5 ≤ x ≤ 1.5. [6]


(c) For – 1.5 ≤ x ≤ 1.5, use your graphs to solve (i) f(x) = 0

Answer: ………………………………………… [1] (ii) g(x) = 4

Answer: ………………………………………… [1]

(iii) fg(x) = g(x). Answer: ………………………………………… [1]

(d) By drawing a suitable tangent, find an estimate of the gradient of the graph of

y = f(x) when x = 0.5.

Answer: ………………………………………… [3] 12. f(x) = x2 + x – 3 g(x) = 2x + 7 h(x) = 2x

(a) Solve the equation f(x) = 0.

Show all your working and give your answers correct to 2 decimal places.

Answer: ………………………………………… [4]

(b) fg(x) = px2 + qx + r Find the values of p, q and r.

Answer: p = ……………………………… [3]

q = ……………………………… [3]

r = ……………………………… [3]


(c) Find g -1(x).

Answer: ………………………………………… [2]

(d) Find x when h(x) = 0.25.

Answer: ………………………………………… [1]

(e) Find hhh(3).

Give your answer in standard form, correct to 4 significant figures.

Answer: ………………………………………… [4] 13. Find the equation of the line passing through the points with co-ordinates (5,9) and (−3,13).

Answer: ………………………………………… [3]


14. The table shows some values for the function y = 11x – 2x2 – 12 for 1 ≤ x ≤ 4.5.


(b) On the grid below, draw the graph of y = 11x – 2x2 – 12 for 1 ≤ x ≤ 4.5. [4]

(c) By drawing a suitable line, use your graph to solve the equation 11x – 2x2 = 11.

Answer: x = ……...… or x =………… [2]

(d) The line y = mx + 2 is a tangent to the curve y = 11x – 2x2 – 12 at the point P. By drawing this tangent, (i) find the co-ordinates of the point P

Answer: ( …………… , …………) [3] (ii) work out the value of m.

Answer: ………………………………………… [2]


15. (a) Complete the table of values for the function f(x) = ("− 𝑥!, 𝑥 ≠ 0. [3]

(b) Draw the graph (next page) of f(x) = (

"− 𝑥! for −3 ≤ x ≤ –0.2 and 0.2 ≤ x ≤ 3. [5]

(c) Use your graph to solve f(x) = –3.

Answer: x = ……...… or x =………… or x =………… [3] (d) By drawing a suitable line on your graph, solve the equation f(x) = 2x – 2.

Answer: x = ……...… or x =………… or x =………… [3] (e) By drawing a suitable tangent, work out an estimate of the gradient of the curve at the point where x = –2. You must show working.

Answer: ………………………………………… [3]


16.

A(5, 10) and B(13, −2) are two points on the line AB. The perpendicular bisector of the line AB has gradient !

3 .

Find the equation for the perpendicular bisector of AB.

Answer: ………………………………………… [4]


17. The equation of the line l in the diagram is y = 5 – x.

(a) The line cuts the y-axis at P. Write down the co-ordinates of P.

Answer: ………………………………………… [1]

(b) Write down the gradient of the line l.

Answer: ………………………………………… [1]


18. (a) Complete the table of values for y = x3 – 3x + 1. [2]

(b) Draw the graph (on the next page) of y = x3 – 3x + 1 for −2.5 ≤ x ≤ 2.5. [4] (c) By drawing a suitable tangent, estimate the gradient of the curve at the point where x = 2.

Answer: ………………………………………… [3] (d) Use your graph to solve the equation x3 – 3x + 1 = 1.

Answer: x = ……...… or x =………… x = ………… [2] (e) Use your graph to complete the inequality in k for which the equation

x3 – 3x + 1 = k has 3 different solutions.

Answer: …………… < k < ……………… [3]


19. (a) f(x) = 2x – 3 g(x) = ("4(

+ 2 h(x) = 3x (i) Work out f(4).

Answer: ………………………………………… [1] (ii) Work out this fh(−1)

Answer: ………………………………………… [2] (iii) Find f-1(x), the inverse of f(x).

Answer: ………………………………………… [2] (iv) Find ff(x) in its simplest form.

Answer: ………………………………………… [2]


(v) Show that the equation f(x) = g(x) simplifies to 2x2 – 3x – 6 = 0. [3] (vi) Solve the equation 2x2 – 3x – 6 = 0. Give your answers correct to 2 decimal places. Show all your working.

Answer: ………………………………………… [4]

(b) Simplify "673"4!"643"7(8

.

Answer: ………………………………………… [4]


20. f(x) = ("6−2x, x ≠ 0.

(a) Complete the table of values for f(x). [3]

(b) On the grid, draw the graph of y = f(x) for –3 ≤ x ≤ –0.5 and 0.4 ≤ x ≤ 2. [5]

(c) Solve the equation f(x) = 2.

Answer: ………………………………………… [1]

(d) Solve the equation f(x) = 2x + 3.

Answer: ………………………………………… [3]

(e) (i) Draw the tangent to the graph of y = f(x) at the point where x = –1.5. [1] (ii) Use the tangent to estimate the gradient of the graph of y = f(x) where x = –1.5.

Answer: ………………………………………… [2]


EXERCISE B 21. f(x) = (

", 𝑥 ≠ 0 g(x) = 1 – x h(x) = x2 + 1

(a) Find fg((

!).

Answer: ………………………………………… [2]

(b) Find g-1(x), the inverse of g(x).

Answer: ………………………………………… [1]

(c) Find hg(x), giving your answers in simplest form.

Answer: ………………………………………… [3]

(d) Find the value of x when g(x) = 7.

Answer: ………………………………………… [1]

(e) Solve the solution h(x) = 3x. Show your working and give your answers correct to 2 decimal places.

Answer: ………………………………………… [4]

(f) A function k(x) is its own inverse where k-1(x) = k(x), For which of the functions f(x), g(x) and h(x) is this true?

Answer: ………………………………………… [1]


2. The table shows some values for the function y = ("6+ 𝑥,𝑥 ≠ 0.

(a) Complete the table of values. [3] (b) On the grid, draw the graph of y = = (

"6+ 𝑥 for –3 ≤ x ≤ –0.5 and 0.5 ≤ x ≤ 4. [5]


(c) Use your graph to solve the equation ("6+ 𝑥 − 3 = 0.

Answer: x = ……...… or x =………… x = ………… [3]

(d) Use your graph to solve the equation ("6+ 𝑥 = 1 − 𝑥.

Answer: ………………………………………… [3]

(e) By drawing a suitable tangent, find an estimate of the gradient of the curve at the point where x = 2.

Answer: ………………………………………… [3]

(f) Using algebra, show that you can use the graph at y = 0 to find √−1; . [3]


3. f(x) = 4 – 3x g(x) = 3-x

(a) Find f(2x) in terms of x.

Answer: ………………………………………… [1]

(b) Find ff(x) in its simplest form.

Answer: ………………………………………… [2]

(c) Work out gg(–1). Give your answer as a fraction.

Answer: ………………………………………… [3]

(d) Find f-1(x), the inverse of f(x).

Answer: ………………………………………… [2]

(e) Solve the equation gf(x) = 1.

Answer: ………………………………………… [3]


4. The point A has co-ordinates (−4, 6) and the point B has co-ordinates (7, −2). Calculate the length of the line AB.

Answer: ………………………………………… [3] 5. Given the function f(x) = 5 – 3x,

(a) Find f(6). Answer: ………………………………………… [1]

(b) Find f(x +2).

Answer: ………………………………………… [1]

(c) Find ff(x), in its simplest form.

Answer: ………………………………………… [2]

(d) Find f-1(x), the inverse of f(x).

Answer: ………………………………………… [2]


6.

The diagram shows the straight line, l, which passes through (0, 3) and (4, 11).

(a) Find the equation of the line l in the form y = mx + c.

Answer: ………………………………………… [3]

(b) Line p is perpendicular to line l. Write down the gradient of line p.

Answer: ………………………………………… [1]


7. f(x) = x2 + 4x – 6

(a) f(x) can be written in the form (x + m)2 = n. Find the value of m and n.

Answer: m = …………………………… [1]

n = …………………………… [2]

(b) Use your answer in part (a) to find the positive solution to x2 + 4x – 6 = 0.

Answer: ………………………………………… [2]


8. f(x) = 3x + 5 g(x) = x2

(a) Find g(3x). Answer: ………………………………………… [1]

(b) Find f-1(x), the inverse function.

Answer: ………………………………………… [2]

(c) Find ff(x). Give your answer in its simplest form.

Answer: ………………………………………… [2] 9. The table shows some values for 𝑦 = 𝑥! − (

!", x ≠0.


(b) On the grid, draw the graph of 𝑦 = 𝑥! − (!"

for −2 ≤ 𝑥 ≤ −0.2 and 0.2 ≤ 𝑥 ≤ 2 [4]


(c) By drawing a suitable line, use your graph to solve the equation 𝑥! − (!"= 2.

Answer: ………………………………………… [3]

(d) The equation 𝑥! − (!"= 𝑘 has only one solution.

Write down the range of values of k for which this is possible.

Answer: ………………………………………… [2]

(e) By drawing a suitable tangle, find an estimate of the gradient of the curve at the point where x = −1.

Answer: ………………………………………… [3]


10. y = x2 – 2x + 𝟏𝟐

𝒙, x ≠ 0.

(a) Complete the table of values below. [2]

(b) On the grid on the next page, draw the graph of y = x2 – 2x + (!"

for −4 ≤ 𝑥 ≤ −0.5 and 0.5 ≤ 𝑥 ≤ 4. [3]

(c) By drawing a suitable tangent, find an estimate of the gradient of the graph at the point (1, 11).

Answer: ………………………………………… [3]

(d) The equation x2 – 2x + 𝟏𝟐𝒙

= k has exactly two distinct solutions. Use the graph to find (i) the value of k

Answer: ………………………………………… [1]

(ii) the solutions of x2 – 2x + 𝟏𝟐𝒙

= k

Answer: ………………………………………… [2]

(e) The equation x2 + ax2 + bx + c = 0 can be solved by drawing the line y = 3x + 1 on the grid. Find the value of a, of b and of c.

Answer: ………………………………………… [3]


11. f(x) = B"6+ "

!, x ≠ 0.

(a) Complete the table of values for f(x). [3]

(b) On the grid, draw the graph of y = f(x) for −5 ≤ 𝑥 ≤ −1.5 and 1.5 ≤ 𝑥 ≤ −5. [5]


(c) Solve f(x) = 0.

Answer: ………………………………………… [1]

(d) By drawing a suitable line on the grid, solve the equation f(x) = 1 – x.

Answer: ………………………………………… [3]

(e) By drawing a tangent at the point (-3, -0.6), estimate the gradient of the graph of y = f(x) when x = −3.

Answer: ………………………………………… [3] 12. f(x) = 2x – 1 g(x) = x2 + x h(x) = !

", where x ≠ 0.

(a) Find ff(3).

Answer: ………………………………………… [2]

(b) Find gf(x), giving your answer in simplest form.

Answer: ………………………………………… [3]

(c) Find f-1(x).

Answer: ………………………………………… [2]

(d) Find h(x) + h(x + 2), giving your answer as a single fraction.

Answer: ………………………………………… [4]

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