Answer:
d. [tex]x=1,4,\:or\:7[/tex]
Step-by-step explanation:
The given equation is
[tex]x^3-12x^2+39x-28=0[/tex]
To find all real solutions using the x-intercept method, we to graph the corresponding function using a graphing tool.
The corresponding function is;
[tex]f(x)=x^3-12x^2+39x-28[/tex]
The real solutions to [tex]x^3-12x^2+39x-28=0[/tex], are the x-intercepts of the graph of the corresponding function.
From the graph the x-intercepts are
(1,0),(4,0) and (7,0).
Therefore the real solutions are
[tex]x=1,4,\:or\:7[/tex]