Question 1156439
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<pre>


(21+2x)*(30+2x) - 21*30 = 756


60x + 42x + 4x^2 = 756


4x^2 + 102x - 756 = 0


x^2 + 51x - 378 = 0


{{{x[1,2]}}} = {{{(-51 +- sqrt((-51)^2+4*1*378))/(2*2)}}} = {{{(-51 +- 75)/4}}}.


Negative root does not work.  The positive root  x = {{{(-51 + 75)/4}}} = 6 is the solution to the problem.


<U>ANSWER</U>.  6 inches.
</pre>

Solved.


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If you want to see many other similar solved problems, look into the lessons

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/Surface-area/Problems-on-the-area-of-a-rectangle-surrounded-by-a-strip.lesson>Problems on the area and the dimensions of a rectangle surrounded by a strip</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/Surface-area/Cynthia-Besch-and-the-rug.lesson>Cynthia Besch wants to buy a rug for a room</A> 

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in this site.


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The referred lesson is the part of this online textbook under the topic 
"<U>Dimensions and the area of rectangles and circles and their elements</U>".


Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
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