Question

sin 2x=-1 решение.
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Answer 1

$sin2x=-1 \ 2x=- frac{pi}{2} +2 pi k,k in Z \ x=- frac{pi}{4} + pi k,k in Z$

Answer 2

sin2x = - 1 
2x = - pi/2 + 2pik   // : 2 
x = - pi/4 + pik, k ∈ Z