Solution
Given the function
Since the coefficient of x^3 = 3
The coefficient of x^2 = - 2
The coefficient of x = 5
The coefficient of x^0 = 2
By applying the synthetic division with 3
The terms in the upper row = 3, -2, 5, 2
The terms in the middle row = 9, 21, and 78
And, the terms in the bottom row = 3, 7, 26, and 80
Since, 3> 0 and all the sign in the bottom row are positive.
Thus, 3 is the upper bond for real roots of this equation.