Question 441508
Use the Quadratic Formula to solve the equation in the interval
[0, 2π). (Round your answers to four decimal places.)
4 tan2 x + 15 tan x − 25 = 0
..
I will assume the first term is 4 tan^2x instead of 4 tanx as given
4 tan^2 x + 15 tan x − 25 = 0
a=4, b=15, c=-25
tanx=[-15+-sqrt(15^2-4*4*-25)]/2*4
       =[-15+-sqrt(625)]/8
       =(-15+-25)/8
       =-40/8 or 10/8
       =-5 or 1.25
using inverse function key for tan
tanx=-5
x=101.3099º (note that calculator will give a reference angle of -78.6900º, but this is not within specified domain for x, hence the angle must be in quadrant II where tan x is also negative)
tanx=1.25
x=51.3402º
ans:
x=101.3099º and 51.3402º in domain[0,2π)