Question 408068
I don't really see how the Cauchy-Schwarz inequality applies to this problem...from what I know, the Cauchy-Schwarz inequality says that for positive numbers {{{a[i]}}} and {{{b[i]}}}, {{{1 <= i <= n}}},


{{{sum(a[i]^2, i = 1, n)sum(b[i]^2, i = 1, n) >= sum(a[i]b[i], i = 1, n)^2}}}.


The best way is to factor {{{x - 25}}} out, leaving


{{{(x - 25)(x^2 - 4) = 0}}}


From here, it is apparent that x = 25, -2, or 2.