Answer:
x-intercept states that the graph crosses the x-axis.
i.,e substitute y=f(x)= 0 and solve for x;
Given the function: f(x) = (x+1)(x-3)(x-4)
By definition of f(x)
Substitute f(x) =0 and solve for x;
(x+1)(x-3)(x-4) = 0
By zero product property: if ab = 0 then either a = 0 or b =0
x+1 = 0 , x-3 =0 and x-4 = 0
⇒ x = -1 , 3 and 4
therefore, the number of x-intercepts are 3