**Find x. Round to the nearest tenth if necessary.**

\(\begin{array}{|rcll|} \hline x\cdot (x+1) &=& 10 \cdot 3 \\ x^2+x &=& 30 \\ x^2+x-30 &=& 0 \\ (x-5)(x+6) &=& 0 \\\\ x_1 &=& 5 \\ x_2 &=& -6 \qquad \text{no solution, because }x \lt 0 \\ \hline \end{array} \)

**d. 5**