Find all the roots of each of the polynomial equations. \( \begin{array}{ll}\text { 9. } x^{3}-2 x^{2}-11 x-6=0 & \text { 10. } x^{3}-11 x^{2}+36 x-26=0 \\ \text { 11. } 2 x^{3}+x^{2}+4 x-15=0 & \text { 12. } x^{3}-5 x^{2}+39 x+45=0 \\ \text { 13. } 2 x^{3}+x^{2}-108 x-54=0 & \text { 14. } x^{3}+2 x^{2}-23 x+6=0 \\ \text { 15. } x^{3}+10 x^{2}+13 x-74=0 & \text { 16. } x^{4}+5 x^{3}+23 x^{2}+51 x=0\end{array} \)

3.18. Determine el máximo comun divisor de los enteros \( 15,18,24 \) y escríbalo como una combinación lineal de \( 15,18,24 \). 3.19. Sea \( a \in \mathbb{Z}^{+} \)tal que \( \operatorname{mcd}(240, a)=1 \), probar que \( 240 \mid a^{4}-1 \).

f) \( (-15 a b c+12 a b-9 a c-3 a) \div(-3 a) \)

Find \( x \). \( \frac{x-1}{3}=\frac{5}{x}+1 \) A. 6.36 OR -2.36 (B) 6.36 (C) 5.46 OR 2.36 (D) No real roots

42. Julio paid \( 7 \frac{3}{4} \% \) sales tax on an item he bought. He figured that if he had bought the item in a neighboring state where the sales tax is \( 8 \frac{1}{4} \% \), he would have paid \( \$ 75 \) more. What was the cost of the item before tax? (C) \( \$ 15,000.00 \) (IS) \( \$ 3,750.00 \) (C) \( \$ 1,500.00 \) (D) \( \$ 150.00 \) (F) \( \$ 37.50 \)

Find \( n \), \( 3 n-6=18 n^{2} \) A) 0.654 (B) -0.488 (C) 0.654 OR -0.488 (D) No real roots