The x intercept means that F(x) = 0
sin(4x)/2x=0
Which means that sin 4x=0
4x E {(-1)^n arcsin 0 +npi | nE Z}
x E {npi/4}
For x between 0 and pi means that x E {0, pi/4, pi/2, 3pi/4, pi}.
I hope that this is the answer that you were looking for and it has helped you.
