5. The area of a bulletin board is 55 square feet. The length is four feet less than three times the width. Find the length and the width of the a bulletin board. a
Hi Jhounsanfreianpiloto, let x represent the width of the rectangle. Then 3x - 4 would represent the length. Using the formula for the area of a rectangle, we can find the values for the length and width.
Area of rectangle:
A = L * W
Substitute for A, L, and W:
55 = (3x - 4) * x
55 = 3x2 - 4x
Move all terms to the same side of the equal sign:
3x2 - 4x - 55 = 0
This can be factored:
(x - 5) * (3x + 11) = 0
Use the zero product rule to solve:
x - 5 = 0
x = 5
3x + 11 = 0
x = -11/3
We can discard the negative solution since the width cannot be negative.
The width of the rectangle is 5 feet.
The length of the rectangle is 3 * 5 - 4, or 11 feet
Answers & Comments
Answer:
width = 5
length = 11
Step-by-step explanation:
let x = width
3x - 4 = length
55 = Area
Solution:
A = LW
55 = (3x - 4) x
55 = 3x^2 - 4x
3x^2 - 4x - 55 = 0
(3x + 11) (x - 5) = 0
3x + 11 = 0 x - 5 = 0
3x = -11
1/3 ( 3x) = -11(1/3) x = 5
x = -11/3
hence, we will use x = 5 since we cannot use a negative number as dimension of sides of polygon.
therefore, width = 5
length = 3x - 4
length = 3(5) - 4
length = 15 - 4
length = 11
Answer:
Hi Jhounsanfreianpiloto, let x represent the width of the rectangle. Then 3x - 4 would represent the length. Using the formula for the area of a rectangle, we can find the values for the length and width.
Area of rectangle:
A = L * W
Substitute for A, L, and W:
55 = (3x - 4) * x
55 = 3x2 - 4x
Move all terms to the same side of the equal sign:
3x2 - 4x - 55 = 0
This can be factored:
(x - 5) * (3x + 11) = 0
Use the zero product rule to solve:
x - 5 = 0
x = 5
3x + 11 = 0
x = -11/3
We can discard the negative solution since the width cannot be negative.
The width of the rectangle is 5 feet.
The length of the rectangle is 3 * 5 - 4, or 11 feet