{2cosx+√2=0
{2sinx+√2 ≠ 0
{cosx=–√2/2;
{sinx ≠ –√2/2
О т в е т. х=(3π/4)+2πn, n ∈ Z
6.
{sin4x=0
{cos4x–1 ≠ 0
{sin4x=0
{cos4x ≠ 1
{4x=πk, k ∈ Z
{4x ≠ 2πn, n ∈ Z
{x=(π/4)·k, k ∈ Z
{x ≠ (π/2)·n, n ∈ Z
(π/4)·k ≠ (π/2)·n
k/4≠n/2
k≠2n
О т в е т. ± (π/4)+πm, m ∈ Z
см. рис.