We are given a piecewise-defined function in a graph. We need to express the function in function notation and determine the x- and y-intercepts.

AlgebraPiecewise FunctionsLinear EquationsInterceptsFunction Notation
2025/4/18

1. Problem Description

We are given a piecewise-defined function in a graph. We need to express the function in function notation and determine the x- and y-intercepts.

2. Solution Steps

First, let's find the equation of each line segment. The break point is at x=1x=1.
For x<1x<1, the line passes through (3,2)(-3, 2) and (1,4)(1, 4). The slope of the line is:
m1=421(3)=24=12m_1 = \frac{4-2}{1-(-3)} = \frac{2}{4} = \frac{1}{2}.
Using point-slope form with the point (1,4)(1, 4), we have
y4=12(x1)y - 4 = \frac{1}{2}(x-1), so y=12x12+4=12x+72y = \frac{1}{2}x - \frac{1}{2} + 4 = \frac{1}{2}x + \frac{7}{2}.
For x1x \ge 1, the line passes through (1,4)(1, 4) and (4,2)(4, -2). The slope of the line is:
m2=2441=63=2m_2 = \frac{-2-4}{4-1} = \frac{-6}{3} = -2.
Using point-slope form with the point (1,4)(1, 4), we have
y4=2(x1)y - 4 = -2(x-1), so y=2x+2+4=2x+6y = -2x + 2 + 4 = -2x + 6.
Therefore, the piecewise function is:
f(x)={12x+72,x<12x+6,x1f(x) = \begin{cases} \frac{1}{2}x + \frac{7}{2}, & x < 1 \\ -2x + 6, & x \ge 1 \end{cases}
Now let's find the x- and y-intercepts.
For x<1x<1, y=12x+72y = \frac{1}{2}x + \frac{7}{2}.
To find the y-intercept, let x=0x=0. Then y=12(0)+72=72=3.5y = \frac{1}{2}(0) + \frac{7}{2} = \frac{7}{2} = 3.5.
To find the x-intercept, let y=0y=0. Then 0=12x+720 = \frac{1}{2}x + \frac{7}{2}, so 12x=72\frac{1}{2}x = -\frac{7}{2}, which means x=7x = -7. Since 7<1-7 < 1, this is a valid x-intercept.
For x1x \ge 1, y=2x+6y = -2x + 6.
If x=0x=0, y=2(0)+6=6y = -2(0) + 6 = 6. This is the y-intercept, but 010 \ge 1 is false.
To find the x-intercept, let y=0y=0. Then 0=2x+60 = -2x + 6, so 2x=62x = 6, which means x=3x = 3. Since 313 \ge 1, this is a valid x-intercept.
So the x-intercepts are 7-7 and 33. The y-intercept is at x=0x=0, which falls in the domain x<1x<1, therefore, y=3.5y=3.5.

3. Final Answer

The function notation is f(x)={12x+72,x<12x+6,x1f(x) = \begin{cases} \frac{1}{2}x + \frac{7}{2}, & x < 1 \\ -2x + 6, & x \ge 1 \end{cases}.
x-intercepts: 7-7 and 33.
y-intercept: 3.53.5.

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