Question

Cos (Pi(4x-9))/4 =√2/2

Answer 1

$\frac{ \pi (4x-9)}{4}= +-\frac{ \pi }{4} +2 \pi n \\ \\ 4x-9=+-1+8n \\ \\ \\ 4x=10+8n \\ 4x=8+8n \\ \\ \\ x=2+2n \\ x=5/2+2n \\ \\ \\ x=2k \\ x=2k+1/2, \\ k\in Z$