18. Write the equation of the following line in function notation
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Answer:
[tex]\LARGE\mathsf{f(x)\:=-\frac{3}{4}x\:+\:-\frac{5}{4}}[/tex]
Step-by-step explanation:
Given the two points from the graph, (-3, 1) and (1, -2). Use these points to solve for the slope using the following formula:
[tex]\LARGE\mathsf{m = \frac {(y_2\: -\: y_1)}{(x_2\: -\: x_1)}}[/tex]
Let (x₁, y₁) = (-3, 1)
(x₂, y₂) = (1, -2)
Substitute these points into the formula:
[tex]\LARGE\mathsf{m = \frac {(y_2\: -\: y_1)}{(x_2\: -\: x_1)}}[/tex]
[tex]\LARGE\mathsf{m = \frac {-2\: -\: 1}{1\: -\: (-3)}\:=\:\frac {-2\: -\: 1}{1\: +\:3}\:=\frac{-3}{4}}[/tex]
m = -¾
Therefore, the slope of the given line is -¾.
Next, we need to determine the y-intercept, which is the point on the graph where it crosses the y-axis. In order to solve for the y-intercept, we must use the slope, m = -¾, and one of the given points, (1, -2), and substitute these values into the slope-intercept form, f(x) = mx + b:
f(x) = mx + b
-2 = -¾( 1 ) + b
-2 = -¾ + b
Add ¾ to both sides to solve for b:
-2 + ¾ = -¾ + ¾ + b
[tex]\LARGE\mathsf{y-intercept\:(b)\:=\:-\frac{5}{4} }[/tex]
Given the slope, m = -¾, and y-intercept, b = [tex]\LARGE\mathsf{-\frac{5}{4}}[/tex], the equation of the line in function notation is:
[tex]\LARGE\mathsf{f(x)\:=-\frac{3}{4}x\:+\:-\frac{5}{4}}[/tex]