Find the dimensions by factoring the area: Polynomials

Question

a. 16x^2+4x

b. x^2-4x-21

c. x^2-36

Factor each completely to find perimeter, length and width.

Answer 1

a. 16x^2+4x

4x(x+1) = 0

4x = 0 x = 0

(x+1) = 0 , x=-1

No shape possible

b. x^2-4x-21

(x+3)(x-7)

----- roots are -3 (extraneous)and 7. 

Length, width = 7. Perimeter = 28. 

c. x^2-36

(x+6)(x-6)

--------roots are -6(extraneous) and 6.

Length, width = 6. Perimeter = 36.