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10 January, 01:32

Area of 320 square feet, the width of the room is 4/5 it's length

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  1. 10 January, 01:55
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    Area=legnth times width or

    a=lw

    if w=4/5l

    and a=320 then subsitute 320 for a dn 4/5l for w

    320=4/5l times l

    multiply both sides by 5 to clear fraction

    1600=4l times l

    ad like terms

    1600=4l^2

    subtract 1600 from both sides

    0=4l^2-1600

    try and factor because if you have xy=0 then x and/or y=0 so

    difference of 2 perfect squares where

    if you have a^2-b^2 then that equals (a-b) (a+b) so

    0 = (2l) ^2 - (40) ^2 = (2l-40) (2l+40)

    so 2l-40=0

    add 40 to both sides

    2l=40

    divide by 2

    l=20

    if

    2l+40=0

    subtract 40 from both sides

    2l=-40

    divide 2

    l=-20

    since meausrements of real objects cannot be negative, wediscard this number

    l=20 is thhe true legnth s

    subsitute

    w=4/5l

    w=4/5 (20)

    w=80/5

    w=16

    legnth=20

    width=16
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