two sides of a rectangel are (x+5) ft and (x-7) ft. the area of the rectangle is 64 ft ^2. what is the value or x ?

Answer 1

A of rectangle = l * w

A = (x+5)(x-7)

64 = (x+5)(x-7)

x² -2x -35 = 64

x² -2x - 99 = 0

(x + 9)(x - 11) = 0

x+ 9 =0 x -11 = 0

x = -9 x= 11

x= -9 is extraneous as it would make the length and width of rectangle negative which does not make sense.

Therefore x= 11 is the solution

Answer 2

(x+5)(x-7)=64

x²-2x-35)=64

x²-2x-99=0

(x-11)(x+9)=0

The useful root is x=11; the other root is extraneous.

The sides are 16 and 4.