Question 837447
the stopping distance d in feet for a car traveling at a speed of s miles per hour depends on car road conditions.
 here are two possible stopping distance formulas: d=3s and d=0.05s^2+s.
:
a.write and solve an equation to answer the question, "for what speed(s) do the two functions predict the same stopping distance? 
:
We can write the equations as equal to each other
.05s^2+s = 3s
simplify, divide both sides by s
.05s + 1 = 3
.05s = 3 - 1
.05s = 2
s = 2/.05
s = 40 mph, both equations will have the same stopping distance
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Graphically
{{{ graph( 300, 200, -20, 100, -100, 400, .05x^2+x, 3x, 120) }}}
note the stopping distance is 120 ft at 40 mph for both equations