Question 809218
Find the first three x-intercepts of the graph of the given function on the positive x-axis.
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f(x) = 9 − 18 cos(x+π/3)
set y=0 
18cos(x+π/3)=9
cos(x+π/3)=9/18=-1/9
inverse cos(1/9)≈1.459455
..
1st intercept
x+π/3=1.459455
x=1.459455-π/3
x≈0.412258
..
2nd intercept
1.459455+2π=7.742640
x=7.742640-π/3
x=6.695442
..
3rd intercept
1.459455+4π=14.125826
x=14.125826-π/3
x=12.978628