If we denote by the coefficients of the matrix , we have to notice that . Now, the question is: what is the vector and what does the Cauchy-Schwarz inequality give?
I need to show that if is an matrix, then for some by estimating the entries of . The hint I am given is that where for some and apply the CS inequality.
I have not done multivariable calc in a VERY long time, and I just can't seem to jumpstart my brain to attack this problem.