math
posted by Karina .
The length of a rectangle is three less than three times the width. The area is 90ft^2. Find the width and the length of the retangle.

first we represent the unknowns using variables,,
let x = width
let 3x3 = length (according to the first statement)
now we set up the equation,, since we are given the area, recall that the area of a rectangle is
A = L*W
where L=length and W=width.
substituting,
90 = (3x  3)(x)
90 = 3x^3  3x
0 = 3x^2  3x  90
we can factor out the 3 and just cancel it (since the other side of equation is zero):
0 = 3(x^2  x  30)
0 = x^2  x  30
since it's factorable,
0 = (x+5)(x6)
x = 5 and x = 6
since measurements can never be negative, we only take the positive root:
x = 6 ft (width) ; and
3x3 = 15 ft (length)
hope this helps~ :)
Respond to this Question
Similar Questions

basic geometric
10. a rectangle has width the same as a side of a square whose perimeter is 20m. the length of the rectangle is 9m. find the perimeter of this rectangle. 34. The width of a rectangular picture is onehalf the length. The perimeter … 
geometric
The perimeter of a rectangular carpet is 70feet. The with is three fourths the length .Find the width. 38. The length of a rectagular room is six times as the width . The perimeter 84 yards. find the width. 39. The width of a rectangle … 
math
The length, l, of a rectangle is 2 feet less than three times the width, w, of the rectangle. The area of the rectangle is 481 square feet. Find the length and width of the rectangle. how do i work this problem out? 
math
The area of a rectangle is 77 yd2 , and the length of the rectangle is 10 yd less than three times the width. Find the dimensions of the rectangle. 
math
If x represents width of rectangle & length is 4 less than 3 times the width? 
math
Two less than three times the width of a rectangle is equal to the length. The area of the rectangle is 65 square ft. What is the length of the rectangle? 
algebra 1
The length of a rectangle is three less than four times its width. If its perimeter is 54, then find its length and width 
Algebra
The length of a rectangle is 2 ft less than three times the width. The area is 60 ft SQUARED. Find the length of the rectangle 
Math Algebra
Solve algebraically using only variable: The length of a rectangle is two less than three times its width. If the area of the rectangle is 65, find the length and the width. (The area of a rectangle is equal to its length times its … 
Algebra
Solve algebraically using only variable: The length of a rectangle is two less than three times its width. If the area of the rectangle is 65, find the length and the width. (The area of a rectangle is equal to its length times its …