Question

What is the slope-intercept form of the function described by this table?

Answer 1

Answer:

y = -4x +2

Step-by-step explanation:

As x-values increase by 1, y-values decrease by 4. The slope of the line is ...

... m = (change in y)/(change in x) = -4/1 = -4

We can use the first (x, y) pair as a point to use in the point-slope form of the equation of a line. That form can be written, for slope m and point (h, k) ...

... y = m(x -h) +k

using m = -4 and (h, k) = (1, -2), we can fill in the numbers to get ...

... y = -4(x -1) -2

... y = -4x +4 -2 . . . . eliminate parentheses

... y = -4x +2 . . . . . . slope-intercept form

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Alternate approach

After you recognize that a change in x of 1 gives a change in y of -4, you can work backward one step to find the table value for y corresponding to x=0. That will be -2+4 = +2. Now, you know both the slope (-4) and the y-intercept (+2), so you can write the equation directly from this knowledge:

... y = -4x +2