How do you use a graphing utility to approximate the solutions of 2tan^2x+7tanx-15=0 in the interval [0,2pi)?

1 Answer
Aug 9, 2018

= 56.31^o, 101.39^o, 236.31^o, 281.39^o in [ 0, 360^o ]

Explanation:

Solving the quadratic equation,

tan x = 1/4( - 7 +- sqrt( 7^2+4(2)(15)) = 1/4( - 7 +- 13 )

= - 5, 1.5.

x = { kpi + arctan ( - 5 )}, {kpi + arctan ( 1.5 )}, k = 0, +-1, +-2, ...#

= { k180^o- 78.69^o }, {k180^o + 56.31^o }

= ( ....101.39^o, 281.39^o... ), ( 56.31^o, 236.31^o..)

= 56.31^o, 101.39^o, 236.31^o, 281.39^o in [ 0, 360^o ]