Oblicz miejsce zerowe funkci określonych wzorem :   1 y=3x-15 2 y=1/2x+4   3 y= -3x - 9

1) 3x-15=0 3x=15 x=5   2) 1/2x + 4=0 1/2x = -4 x = -8   3) -3x - 9 = 0 -3x = 9 x = -3  

1.  f(x) = 0  <=> 3x-15 = 0                           3x = 15 |:3                              x = 5 2. f(x) = 0 <=> 1/2x + 4 = 0                             1/2 x = -4| razy 2                                    x = - 8   3. f(x) = 0 <=> -3x - 9 = 0                           -3x = 9 |:(-3)                                x = - 3     * <=> ----- wtedy i tylko wtedy