\hspace{-16}$It is known about real $\mathbf{a}$ and $\mathbf{b}$ that the inequality $\mathbf{a\; cosx +b\;cos3x >1}$\\\\ has no real solutions.then Prove that $\mathbf{\mid b\mid \leq 1}.
-
UP 0 DOWN 0 0 0
\hspace{-16}$It is known about real $\mathbf{a}$ and $\mathbf{b}$ that the inequality $\mathbf{a\; cosx +b\;cos3x >1}$\\\\ has no real solutions.then Prove that $\mathbf{\mid b\mid \leq 1}.