Answer:
x = 9
Explanation:
A = 56
L = x + 2
W = 2x - 5
A = L * W
56 = (x+2)(2x - 5)
re-write
(x+2)(2x - 5) = 56
x^2 - 5x +4x - 10 = 56
x^2 - x - 10 - 56 = 0
x^2 - x - 66 = 0
a = 1, b = -1 and c = -66
-b +/- √(b^2 - 4ac)
x = -------------------------------------
2a
since dimension can't be a negative number so we only use positive
-b + √(b^2 - 4ac)
x = -------------------------------------
2a
-(-1) + √((-1)^2 - 4(1)(-66))
x = -----------------------------------------
2(1)
1+ √265
x = -------------
2
x = 8.64
x = 9 (rounded to the nearest whole number)