need someone to check my work

abel muroi

Junior Member
Joined
Jan 13, 2015
Messages
210
i was given this problem 2 sin2 x + 3 = 4 and was told to find ALL possible solutions

so here is my work...


2 sin2 x + 3 = 4
2 sin2 x = 1
sin2 x = 1/2
sin x = +- 1/(squareroot 2)

so the sin of 1/(squareroot 2) is 45 degrees

the general solution must be x = pi/4 + k*2pi



do i have the correct general solution?
 
i was given this problem 2 sin2 x + 3 = 4 and was told to find ALL possible solutions

so here is my work...


2 sin2 x + 3 = 4
2 sin2 x = 1
sin2 x = 1/2
sin x = +- 1/(squareroot 2)

so the sin of 1/(squareroot 2) is 45 degrees

the general solution must be x = pi/4 + k*2pi



do i have the correct general solution?
No, this is not complete at all. There are 4 solutions to this equation in the domain (!!) [0, 2pi). You only found 1 solution. How about solutions in the other 3 quadrants? Might there be solutions there? Adding on the k*2pi to the solution you found is correct.
 
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