SOLUTION: Their is a rectangle and its legnth is d-12 and the width is d. If the area is 28 square units, what is the value of d?

Question 446629: Their is a rectangle and its legnth is d-12 and the width is d. If the area is 28 square units, what is the value of d?
Found 2 solutions by chriswen, stanbon:
Answer by chriswen(106) (Show Source): You can put this solution on YOUR website!
A=l*w
28=(d)(d-12)
28=d^2-12d
d^2-12d-28=0

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=256 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 14, -2. Here's your graph:

The answer must be positive so the answer is 14.
d=14
d-12=2
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
There is a rectangle and its length is d-12 and the width is d. If the area is 28 square units, what is the value of d?
----
Area = length*width
---
28 = (d-12)d
d^2-12d-28 = 0
---
Factor using Inverse FOIL:
d^2-14d+2d-28 = 0
d(d-14)+2(d-14) = 0
(d-14)(d+2) = 0
----
Positive solution:
width = d = 14
length = d-12 = 2
=======================
Cheers,
Stan H.
RELATED QUESTIONS
the area of a rectangle is 96 square feet.the legnth is 4 more than 5 times the width.... (answered by vheroli)
what could be the legnth , heigth . and width of a rectangle if its are is 100 cubic... (answered by JulietG)
The legnth of a rectangular rug is twice its width. If the area of the rug is 450 square (answered by w_parminder)
The perimeter of a rectangle is 188m. The legnth is 8m more than twice the width. What is (answered by ewatrrr)
The length of a rectangle exceeds its width by 7 units and its area is 228 square units.... (answered by Alan3354)
The length of a rectangle exceeds its width by 7 units and its area is 228 square units.... (answered by scott8148,2332)
If the legnth of one side of a rectangle is 8 and the legnth of a diagonal is 10 , find... (answered by scott8148)
the legnth of the rectangle is 15 inches than its width the area is 1350 square inches... (answered by richwmiller)
the area of a rectangle is 155 square units. what would its new area be if its width were (answered by rapaljer)