Answer:
C. 19 ft
Step-by-step explanation:
Let
Width = x
Length = x + 10
Area = 171 ft²
Area of the floor = length × width
171 = x + 10 * x
171 = x² + 10x
x² + 10x - 171 = 0
Solve the quadratic equation using factorization method
Factors are 19x and -9x
x² + 19x - 9x - 171 = 0
x(x + 19) -9(x + 19) = 0
(x + 19) (x - 9) = 0
x = -19 or x = 9
The value of x can not be negative
Therefore, x = 9 ft
Width = x
= 9 ft
Length = x + 10
= 9 + 10
= 19 ft
