alisha
posted by Anonymous .
a candle is a foot tall after burning an hour. after 4 h it is 10.5 in. tall. write a linear equation to model the height y of the candle after x hours. and how many hours will the candle be 6 inches tall??
plz explain the work .....

plz...help

look at it as ordered pairs of the form
(time, height)
you are given 2 such points, namely
(1,12) and (4,10.5)
slope = (10.5+12)/(41)
= 1.5/3 = .5 or =1/2
using height = m(time) + b (remember y=mx+b ?)
and using the point (1,12)
we get
12 = (1/2)(1) + b
b = 12.5
so height = time/2 + 12.5
you want height to be 6
6 = time/2 + 12.5
12 = time + 25
time = 2512
= 13 
thanks so so so much
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