This question is solved applying the formula of the area of the rectangle, and finding it's width. To do this, we solve a quadratic equation, and we get that the cardboard has a width of 1.5 feet.
Area of a rectangle:
The area of rectangle of length l and width w is given by:
w(2w + 3) = 9
From this, we get that:
Solving a quadratic equation:
Given a second order polynomial expressed by the following equation:
.
This polynomial has roots 
such that 
, given by the following formulas:
In this question:
Thus a quadratic equation with 
Then
Width is a positive measure, thus, the width of the cardboard is of 1.5 feet.
Another similar problem can be found at brainly.com/question/16995958
A should be the right answer because 4*5/4=5 + 5*2=10 and 5+10=15.
The absolute value of a real number a is a when a≥0, or -a when a<0. The absolute value of -6 is 6. The absolute value of 4 is 4.
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It’s easiest to think about it this way:
If the pond is 15 feet wide, then adding 3 feet to each side would increase the side length to the square by six feet (3 feet on each side). This makes the area within the square equal to 18x18 feet, or 324 square feet. But, this isn’t the area of the sidewalk, it’s the area of the sidewalk plus the area of the pool.
The pool is fifteen feet wide, which means that it has an area of 225 square feet. So, to find the area of the side walk, we can subtract the area of the pool from the area of the pool and sidewalk, which will give us the area of the sidewalk by itself.
324-225=99 square feet.
The pool has an area of 225 square feet, and the sidewalk has an area of 99 feet.
