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 Mathematics  Form 3  Chapter 9 Straight Lines     Mathematics  Form 3  Chapter 9 Straight Lines

 PT3 Standard Practice  9  Section B  (b)  Equation of line PQ    2.  (a)  (i)   k located at line y = 3
               y = –  5  x + 5 ..............(1)                    Therefore k(a, 3)
 Section A    1.  Diagram  Equation  3                              y = 2x – 4
 Rajah  Persamaan      Equation of line RS
 6 – (–4)                                                             3 = 2(a) – 4
   1.  Gradient of KL =   (a)   y       y = x + 3 ....................(2)
 8 – (–2)                                                           a = 3.5
         = 1  K  2  y = –    + 2     (1) = (2),                     ∴ k(3.5, 3)
 2
                              
      Equation of KL  x  5       –   5  x + 5 = x + 3  × 3
      y = x + c  O  5  L  3                                     (ii)  x = –4
      at L(8, 6)   (b)   –5x + 15 = 3x + 9                     (iii)  m ML  = m KN
      6 = 8 + c  y   x =   3                                            = 2
      c  = –2  K(8, 4)  4
 1                          3                                       y = 2x + c
      ∴ y = x – 2  y =  x     Substitute x =    into (2)
 x  2                       4                                       Substitute x = –4, y = 0,
      Answer: D  L  O     y =   3   + 3
                  4                                                 0 = 2(–4) + c
   2.   4x + 3y = 15     y =   15                                   c  = 8
         3y = –4x + 15    2.   Equation  Point  4                   ∴ y = 2x + 8
 4  Persamaan  Titik  3 15
         y = –   x + 5       ∴ k   ,                          (iv)  Coordinates P = (p, 0)
 3                 4  4
 (a)  y = 3x – 7  (6, 11)  ✓                                        Substitute x = p, y = 0 into y = 2x – 4,
 4
      ∴ m = –  , c = 5  (c)  Substitute x = 2, y = 8,               0 = 2p – 4
 3
 (b)  –5x + y = 2  (–3, –13)  ✓  y =   k  x + 5m                    p = 2
      Answer: B    3                                                Length of MP  = 2 – (–4)
 1
   3.  x-intercept, y = 0  (c)  3y =  x + 8  (2, –3)  ✗  8 =  2k  + 5m            = 6 units
 2                  3
        2x – 3y = 6       24 = 2k + 15m ...................(1)      Area of KLMP = (3 × 6)
 1
       2x – 3(0) = 6  (d)   1 y +  x = 1  (–10, 6)  ✗     Substitute x = –5, y = –13          = 18 units 2
         2x = 6  3  5  k
         x = 3    y =   x + 5m                             (b)  2x + 3y – 4 = 0
 Section C          3                                                   3y = –2x + 4
      ∴ x-intercept = 3   –13 =   –5k   + 5m
                                                                               2
   1.  (a)  (i)   Rhombus has equal length of sides.  3                  y = –   x +   4
      Answer: B                                                                3    3
    OK = KL = LM = MO       –39 = –5k + 15m ...............(2)                 2
 2
   4.  m KL  = –1, c = –5          OK = (–5)  + 12 2      (1) – (2)     gradient, m = –   3
 = 13 units   24 – (–39) = 2k – (–5k)
      ∴ equation of the straight line KL is                (c)  5x + 2y = 8
          y = –x – 5  ∴ OM = 13 units  63 = 7k
         M(–13, 0)    k = 9                                     Divide both sides by 8,
      Answer: C     Substitute k = 9 into (1)                   5x   2y    8
    (ii)  m KO  =   12 – 0                                      8   +    8   =   8
 2  –5 – (0)   24 = 2(9) + 15m
   5.     y –  x = 5                                             x   y
 3              = –  12  15m = 6                                8   +    = 1
                                                                     4
         3y – 2x = 15  5  2
       2x – 3y + 15 = 0  y = mx + c  m =  5                     5
 12                                                             Therefore, x-intercept =   8
      Answer: C  y = –   x + c     ∴ m =   2  , k = 9                                  5
 5                   5                                          y-intercept = 4
 Substitute x = 0, y = 0,
 c = 0
 Equation of LM

    y = –  12 x
 5
    (iii)  y = 12
 53  © Penerbitan Pelangi Sdn. Bhd.  © Penerbitan Pelangi Sdn. Bhd.  54

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 BOOKLET ANS MATH F3.indd   28                                                            03/01/2020   10:21 AM
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