Hello if someone would be able to show me step by step how t
Hello, if someone would be able to show me step by step how to do this problem so I could better understand it, it would be greatly appreciated.
Use algebraic methods to find all (exact) solutions:
2sin2x+7sinx=4
Solution
2sin^2x +7sinx =4
2sin^2x +7sinx -4 =0
solve the quadratic by factorisation:
2sin^2x +8sinx -sinx -4 =0
2sin(sinx +4) -1(sinx +4) =0
(2sinx -1)(sinx+4) =0
sinx= 1/2 ; sinx=-4
Neglect sinx=-4 as sinx>=-1
So, sinx =1/2
x= sin^-1(1/2)
x= pi/6 , pi-pi/6 = pi/6 , 5pi/6
Solution : interval [0, 2pi) x= pi/6 , 5pi/6
General solution : x= pi/6 +2k*pi , 5pi/6 +2k*pi
where k is any integer
