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Find an expression for the length of a side of a square with an area of 9n^2+54n+81

User LuckyStarr
by
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1 Answer

4 votes
Answer: s = 3n + 9 .
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Step-by-step explanation:
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All squares are rectangles.

A square is a rectangle with 4 (FOUR) EQUAL side lengths.

A square has the same length and same length.

The formula for the area, "A", of a square is:

A = s² ; in which "s" is the side length of the square.


So, given: A = 9n² + 54n + 81 ; Find "s" ;

→ A = s² ;

↔ s² = A ;

Plug in our value given for "A" ;

→ s² = 9n² + 54n+ 81 ;

Take the positive square root of EACH SIDE of the equation; to isolate "s" on one side of the equation; & to solve for "s" (the side length);

Note: We take the "positive" square root" ; since the "side length of a square cannot be a "negative value" ;

→ √(s²) = √(9n² + 54n + 81) ;

Take the value under the square root sign:

"9n² + 54n + 81" ; and factor out a "9" ;

→ 9(n² +6n + 9)

And rewrite as:

√[9(n² + 6n + 9)] ;
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Note: √[9(n² + 6n + 9)] = √9 * √(n² + 6n + 9) ;

√9 = 3 ;

√(n² + 6n + 9) is a perfect square; that is: √(n² + 6n + 9) = (n + 3 ) ;

So, √9 *√(n² + 6n + 9) = 3 * (n + 3) = 3*n + 3*3 = 3n + 9 ;

Rewrite:

√(s²) = 3n + 9 ;
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s = 3n + 9 .
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User Maiasaura
by
7.5k points
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