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?

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Answer 1 · 2018-06-21T17:27:47

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.

Answer 2 · 2018-06-21T17:34:26

#x~~274 min~~4.6 hrs#

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