so let the width be x.
by doing so, it will make it easier to solve.
since the question states that the length is three times the width, the length will be 3x.
to find area: length × width
therefore, length: 3x and width is x
area of reactangle:
3x × x= 3x^2
subtitute area=57units square
57 =3x^2
x^2=57÷3
x^2=19
x= square root 19
now, since you square root, there will be two answers. one positive and the other negative. based on this question x have to be positive as length of an object cannot be negative.
x= square root 19
x=4.3588989435
=4.36 units
or
x= -4.3588989435
= -4.36units (reject)
now subtitute x=4.3588989435 to find length and width.
It is best to subtitute with raw numbers.
length:
3 × (4.3588989435)
= 13.0766968306
=13.08 units
width:
4.3588989435 = 4.36 units
dimension:
rectangle with a length of 4.36 units and width of 13.06 units.