Đáp án:
$\text{TXĐ: D=R}$
`y' = m.cosx + 7`
$\text{Để hàm số đồng biến R : }$
`=> y' ≥ 0 `
`=> m.cosx + 7 ≥ 0 `
`=> ` \(\left[ \begin{array}{l}-m+7≥0\\m+7≥0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}m ≤ 7 \\m ≥ -7\end{array} \right.\)
`<=> -7 ≤ m ≤ 7`
`<=> m ∈ { -7,-6,-5,-4,-3,-2,-1,0,1,2,3,4,5,6,7 }`