Solve the problem.
-Elissa wants to set up a rectangular dog run in her backyard. She has 20 feet of fencing to work with and wants to use it all. If the dog run is to be x feet long, express the area of the dog run as a function of x.
A) $A ( x ) = 12 x ^ { 2 } - x$
B) $A ( x ) = 9 x - x ^ { 2 }$
C) $A ( x ) = 10 x - x ^ { 2 }$
D) $A ( x ) = 11 x - x ^ { 2 }$

Question

Solve the problem.
-Elissa wants to set up a rectangular dog run in her backyard. She has 20 feet of fencing to work with and wants to use it all. If the dog run is to be x feet long, express the area of the dog run as a function of x. 
A) $A ( x ) = 12 x ^ { 2 } - x$
B) $A ( x ) = 9 x - x ^ { 2 }$
C) $A ( x ) = 10 x - x ^ { 2 }$
D) $A ( x ) = 11 x - x ^ { 2 }$

Quizplus · Accepted Answer

The perimeter of the rectangle is given as $2x + 2y = 20$, where $x$ is the length and $y$ is the width. Solving for $y$, we get $y = 10 - x$. The area $A$ of the rectangle is $xy$, substituting $y$ with $10 - x$, we get $A(x) = x(10 - x) = 10x - x^2$.

Solve the Problem A(x)=12x2−xA ( x ) = 12 x ^ { 2 } - xA(x)=12x2−x

Solve the Problem $A ( x ) = 12 x ^ { 2 } - x$