Question

If an area of the rectangle below is 39 square feet, sides are x-2 and x+8 find the area of x

Answer 1

Answer:

x  = 5.

Step-by-step explanation:

The area of a rectangle can be determined by the following formula.

A = l ⋅ w  

l  stands for length or the longer side.

w  stands for width or the shorter side.

Now, we can plug the values we are given into the equation.

A = ( x − 2 ) ⋅ ( x + 8 )

The easiest way to multiply is to follow the acronym FOIL , which stands for First Outside Inside Last, and dictates the order in which you multiply these terms.

A = x 2 + 8 x − 2 x −16 = x 2 + 6 x − 16

Now, we can plug in the given value for the area.

39 = x 2 + 6 x − 16  

Next, we simplify by moving all terms to one side and factor the equation.

0 = x 2 + 6 x − 55

Finally, we factor the equation. This means we reverse-FOIL, trying to determine the two things that we multiplied together.

0= ( x − 5 ) ⋅ ( x + 11 )

If the equation ultimately equals zero, either  ( x − 5 )  or  ( x + 11 )  or both equal zero. Therefore, we set each equal to zero to find the value of  

x .

x − 5 = 0 x = 5 x + 11 = 0

x = − 11

Since  x  is a length, we know it cannot be negative. Thus, we can conclude that it equals 5.