The width of a rectangular garage is 8 feet less than the length. How do you express the perimeter of the garage as a function of the length?

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Answer 1 · 2017-02-26T13:29:39

#P = 4(l - 4)#

We can call the length of the garage #l#.

Therefore the width, or we can call it #w#, of the garage is #l - 8# or #w = l - 8#

The formula for the perimeter of a rectangle is:

#P = 2(w + l)#

We can substitute #l - 8# for #w# giving:

#P = 2(l - 8 + l) ->#

#P = 2(l + l - 8) ->#

#P = 2(2l - 8) ->#

#P=2(2(l - 4)) ->#

#P = 4(l - 4)#