The distance a marathon runner covers can be modeled by the function d(x)=153.8x+86. d represents distance (m) and x represents time (min). ow long will it take the runner to run the 42,2km race?

2 Answers
Jun 21, 2018

The answer is the solution of d(x)=42200"m" (because 42.2"km"=42.2*1000=42200"m")

The equation can be solved as follows.

153.8x+86=4200

Subtract both sides by 86.

153.8x=42114

Divide both sides by 153.8.

x~~273.8

As x represents the time in minutes, it will take the runner about 273.8 minutes.

Jun 21, 2018

x~~274 min~~4.6 hrs

Explanation:

d(x)=153.8x+86
d=42.2km*1000m/1km=42200m
153.8x=42200-86
153.8x=42114
x~~274 min~~4.6 hrs