Question 1185996
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The length of a rectangle is 5 cm more than 3 times its width. 
The area of the rectangle is 1428 square cm. Find the length and width of the rectangle.
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<pre>
width = x

length = 3x + 5


Area equation


    x*(3x + 5) = 1428.


Simplify and solve


    3x^2 + 5x - 1428 = 0

    {{{x[1,2]}}} = {{{(-5 +- sqrt((-5)^2 + 4*3*1428))/(2*3)}}} = {{{(-5 +- 131)/6}}}.


Use the positive root, only:  x = {{{(-5 + 131)/6}}} = 21.


<U>ANSWER</U>.  The width is 21 cm;  The length is 3*21+5 = 68 cm.


<U>CHECK</U>.  21*68 = 1428 cm^2.    ! Correct !
</pre>

Solved.