Answer:
-4 or 7
Step-by-step explanation:
Let x represent the number. Then the problem statement tells us ...
x^2 -2x = 28+x
x^2 -3x = 28 . . . . . subtract x
x^2 -3x +2.25 = 30.25 . . . . add the square of half the x coefficient
(x -1.5)^2 = 30.25 . . . . . . . . write the left side as a square
x -1.5 = ±5.5 . . . . . . . . . . . . take the square root
x = 1.5 ±5.5 = {-4, 7} . . . . . . . add 1.5
The number may be either -4 or 7.
