Question

Cos (Pi(4x-9))/4 =√2/2

Answer 1

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