Question

The width of a rectangle is the length minus 4 units. The area of the rectangle is 12 units. What is the width in units of the rectangle

Answer 1

W=2 units

Explanation:

Length=L

Width=L-4

Area of a rectangle= L*W

L(L-4)=12

L^2-4L=12

L^2-4l-12=0

Now we have a quadratic equation

(L-6)(L+2)=0

L=6, L=-2

L cannot be -2 because it is negative, so L must be 6.

BUT it is asking for the width

and it is given that the width is the length minus 4 units, so

6-4= 2 units

Answer 2

width = 2 units

Explanation:

If the length of a rectangle is (x) units, then that means that the width of a rectangle is x - 4 units.

the area of a rectangle is length * width

so just substitute the values that we have now.

x (length) * (x-4) width = 12 (area of rectangle)

so that gives us

x^2 - 4x =12

subtract 12 from both sides

x^2 - 4x - 12 =0

now factor this equation

x^2 + 2x - 6x -12 = 0

x(x+2) - 6(x+2) = 0

(x-6)(x+2) = 0

x = 6, or x = -2 REMEMBER THAT VALUE OF x = LENGTH, IT CANNOT BE NEGATIVE AS YOU CANT HAVE NEGATIVE VALUE OF A SIDE

length = 6, and width = 6 -4 = 2