Precalculus (10th Edition)

$25x^2+16<40x$, I subtract $40x$ from both sides and then factor the trinomial: $25x^2-40x+16<0\\ (5x-4)^2<0$ The square of all real numbers is non-negative, hence for any real number, th value of $(5x-4)^2$ is never negative. Thus, the given inequality has no solution.