Rewrite the explicit formula in function form. The identify the y intercept of the function.
an = 9-3(n-1)

y-intercept: (0, 12)

Step-by-step explanation:

= 9 − 3 (n − 1)

Use the slope-intercept form to find the slope and y-intercept.

  The slope-intercept form is y = mx + b, where m is the slope and b is the y-intercept.

     y = mx + b

  Find the values of m and b using the form y = mx + b.

     m = −3

     b = 12

  The slope of the line is the value of m, and the y-intercept is the value of b.

     Slope: −3

     intercept: (0, 12)

Any line can be graphed using two points. Select two x values, and plug them into the equation to find the corresponding y values.

  Find the x-intercept.

     To find the x-intercept(s), substitute in 0 for y and solve for x.

        0 = −3x + 12

      Solve the equation.

        Rewrite the equation as −3x + 12 = 0.

              −3x + 12 = 0

         Subtract 12 from both sides of the equation.

              −3x = −12

         Divide each term by −3 and simplify.

              x = 4

     x-intercept(s) in point form.

     x-intercept(s): (4, 0)

  Find the y-intercept.

     To find the y-intercept(s), substitute in 0 for x and solve for y.

        y = −3 ⋅ 0 + 12

   Solve the equation.

     Remove parentheses.

           y = −3 ⋅ 0 + 12

       Simplify −3 ⋅ 0 + 12.

           y = 12

     intercept(s) in point form.

     intercept(s): (0, 12)

  Create a table of the x and y values.

      x | y

     0 | 12

     4 | 0

Graph the line using the slope and the y-intercept, or the points.

Slope: −3

intercept: (0, 12)

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