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24.  (a)                                         3.  (a)  m =  9 – 5   = 2
                             f(x)                                                2 – 0
                                                                              y = mx + c
                            4                                                  5 = 2(0) + c

                           3.5                                                 c = 5
                                f(x) = 5 log (x + 2)                          y = 2x + 5
                            3
                                                                             –3 = 2d + 5
                           2.5                                                d = –4
                                                                                                                [3]
                            2
                                                                          (b)  m m  = –1
                           1.5                            x                    1  2  1
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                                                   f (x) =10    – 2            m  = –
                                                          5
                                                    –1
                            1                                                    2   2
                                                                                y = mx + c
                           0.5                                                        1
                                                                                        2
                                                                                    1
                                                                               –3 =   –    (–4) + c
                                                                                      2
                             0   0.5  1  1.5  2  2.5  3  3.5  4  x             –3 = 2 + c
                                                                                 c = –5
                                                                                     1
                                                               [2]              y = –  x – 5
                         (b)  Let f (x) = y                                          2                          [2]
                                −1
                             5 log(y + 2)  = x
                                     x                                                  2       2
                                log 10   = log(y + 2)                     (c)  AB =  √(2 – 0)  + (9 – 5)
                                     5
                                          x                                     = √20
                                           5
                                 f (x)  = 10  − 2                               = 2√5
                                  −1
                                                               [3]
                                                                             BC =  √[0 – (–4)]  + [5 – (–3)]
                                                                                           2
                                                                                                     2
                       7    Straight Line Graphs                                = √80
                                                                                = 4√5
                                2
                       1.  (a)  2(0)  − p(−4) = 8                             AB : BC
                                 −p(−4) = 8                                   2√5 : 4√5
                                     p = 2                                     1 : 1
                                                                             e = 1, f = 2
                                 2
                              2x  − p(0) = 8                                                                    [3]
                                      2
                                    2x  = 8
                                      2
                                     x  = 4                             4.  Point C,
                                     x = ±2
                                                                             3
                            Q(2, 0), S(−2, 0)                             x =  (4 – 4) ×  5 4  + 4
                                                                                     4
                                                               [2]          = 9
                         (b)  Area of ΔQRS                                           5
                                                                             3
                           =  4 × 4  = 8 unit                             y =  (4 – 0) ×  4 4  + 8
                                       2
                             2                                 [1]          = 13
                       2.  3x + 2y = 12                                   C(9, 13)
                             2y = 12 − 3x                                   m  =   8 – 4
                              y =  12 – 3x                                   1   4 – 0
                                    2                                          = 1
                                   3
                              y = –  x + 6
                                   2                                        m m  = –1
                                                                             2
                                                                           1
                         Gradient = −  3                                    m  =  –1
                                                                             2
                                    2                                            1
                         y = mx + c                                            = –1
                              3
                         2 = −  (−1) + c                                    13 = –1(9) + c
                              2                                              c = 22
                            1
                         c =                                                 y = –x + 22
                            2                                                                                   [3]
                              3
                         y = –  x +  1
                              2   2                            [3]
                                                                                                     Answers    181







         Answers Add Math.indd   181                                                                             14/03/2022   12:29 PM
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