[tex]\displaystyle\bf\\3x^{2} +5x < 0\\\\3x\Big(x+1\frac{2}{3} \Big) < 0\\\\x\Big(x+1\frac{2}{3} \Big) < 0\\\\\\+ + + + + \Big(-1\frac{2}{3} \Big) - - - - - \Big(0\Big) + + + + + \\\\Otvet: \ x\in \Big(-1\frac{2}{3} \Big \ ; \ 0\Big)[/tex]