Page 151 - Mathematics
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0 = −−
                          2( 2) c+
                          c = − 4
               From  y = mx +  , c it implies that,

                          y =  −  2x −  4
               Therefore, the equation of the straight line is  y =  −  2x −  4.                 Tanzania Institute of Education





               Example 6.23

               Find the gradient and y-intercept in each of the following lines:
               (a) 12x +  4y −  15 =  0           (b)  24 8x−  −  3y =  0

               Solution
               (a)  Given 12x +  4y −  15 =  0.

                    Make y  the subject of the formula. Thus,

                    4y =  −  12x +  15
                    Dividing by 4 both sides of the given equation gives,
                             15
                    y =  −  3x +
                              4
                                                                    3
                      Compare this equation with  y mx c=  +  gives m = −  and c = 15 . Thus,
                                                                               4
                      15 
                      0,     is the y-intercept.
                       4 
                                                                    
                    Therefore, the gradient is –3 and the y-intercept is 0,  15     .
                                                                    
                                                                       4 
               (b)   Given  24 8x−  −  3y =  0.
                    Make y  the subject of the formula:

                    −  3y =  8x −  24.
                    Dividing by –3 on both sides gives,

                         8
                    y =  −  x +  8
                         3
                                                                     8
                    Compare this equation with y =  mx c+  to get   m = −  and c = 8.              Mathematics Form One
                                             8                       3
                    Therefore, the gradient is  −  and the  y -intercept is (0, 8).
                                             3




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                                                                                        25/10/2024   09:51:58
   Mathematics form 1.indd   145                                                        25/10/2024   09:51:58
   Mathematics form 1.indd   145
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