This is the same as y = x+13
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Explanation:
Let's find the slope
I'll use the first two rows as the (x1,y1) and (x2,y2) points
m = (y2-y1)/(x2-x1)
m = (19-18)/(6-5)
m = 1/1
m = 1
The slope is 1.
Now apply the point slope formula and solve for y
y - y1 = m(x - x1)
y - 18 = 1(x - 5)
y - 18 = x - 5
y = x-5 + 18
y = x + 13
f(x) = x + 13 is the final answer
As a check, note how something like x = 5 leads to...
f(x) = x+13
f(5) = 5+13 ... replace x with 5
f(5) = 18
We see that x = 5 leads to f(x) = 18. That verifies the first row. I'll let you check the remaining three rows.
The equation y = x+13 has slope 1 and y intercept 13.