What number must you add to complete the square? x^2+26x=11

Cameron made 1 loaf of bread. his family ate 4/6 of the loaf of bread. how much of the loaf of bread remains? /

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

Me find the value of x each figure.