We'll establish the dimensions of the original
rectangle:
- the width: x
-
the length: x + 2
The area of the original rectangle
is:
A1 = x*(x+2)
We'll
establish the dimensions of the new formed rectangle:
-
the width: 2x
- the length: (x + 2) + 4 = x +
6
The area of the new rectangle
is:
A2 = 2x(x+6)
We know from
enunciation that the new area is 75 more than the area of the original
rectangle.
A2 = 75 +
A1
2x(x+6) = 75 + x(x+2)
We'll
remove the brackets:
2x^2 + 12x = 75 + x^2 +
2x
We'll move all terms to one
side:
2x^2 + 12x - 75 - x^2 - 2x =
0
We'll combine like
terms:
x^2 + 10x - 75 =
0
We'll apply the quadratic
formula:
x1 = [-10+sqrt(100 +
300 )]/2
x1 = (-10+20)/2
x1 =
5
x2 = (-10-20)/2
x2 =
-15
Since the measure of a side cannot be negative, we'll
reject the second negative value.
So, the
width of the original rectangle
is:
x = 5
inches
the length: x + 2 = 7
inches
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