7. 3−2x ≥ 8x−1

\(3-2x\geq 8x-1\)

\(3+1\geq 8x+2x\)

\(4\geq 10x\)

\(x\leq \frac{2}{5}\)

Ответ: \(x\in\left(-\infty;\frac{2}{5}\right]\).