what is the value of c that completes the square? z2(squared)+11/8z+c

z^2 + (11/8)z + c

Take 1/2 of 11/8   =  11/16......now......square it  =    121 / 256......   this is "c"

So we have

z^2 + (11/7)z + 121 / 256 =  

(z + 11/16) ^2