1)4x=π/2+πn,n∈Z
x=π/8+πn/4,n∈Z
2)5x=-π/2+2πn,n∈Z
x=-π/10+πn/5,n∈Z
3)3x-1=πn,n∈Z
3x=1+πn,n∈Z
x=1/3+πn/3,n∈Z
4)2x+π/4=2πn,n∈Z
2x=-π/4+2πn,n∈Z
x=-π/8+πn,n∈Z
5)[sin3x+1=0⇒sin3x=-1⇒3x=-π/2+2πn,n∈∈Z⇒x=-π/6+2πn,n∈Z
[sinx/2-1=0⇒sinx/2=1⇒⇒x/2=π/2+2πk.k∈Z⇒x=π+4πk,k∈Z
6)[cos4x=0⇒4x=π/2+πn,n∈Z⇒⇒x=π/8+πn/4,n∈Z
[sinx/2=0⇒x/2=πk,k∈Z⇒x=2πk,k∈Z