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Answer: f(x) = (-1/2)x+1, choice B</h3>
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Explanation:
The diagonal line passes through 1 on the vertical y axis. So the y intercept is b = 1. This means the location of the y intercept is (0,1).
Start at (0,1) and move down 1 and to the right 2 to arrive at (2,0). This is another point on the diagonal line. The motion of "down 1 and right 2" is effectively the slope
slope = rise/run = -1/2
rise = -1, run = 2
The rise being negative means we have gone downhill as we move to the right.
With m = -1/2 as the slope and b = 1 as the y intercept, we go from y = mx+b to y = (-1/2)x+1
The last thing to do is replace y with f(x) to get f(x) = (-1/2)x+1 as the final answer.
0.5 x 4 = 2 feet / 2 feet in 4 seconds
15 - 2 = 13
New depth: 13 feet
0.4 x 3 = 1.2 feet / 1.2 feet in 3 seconds
13 - 1.2 = 11.8
New depth: 11.8 feet
