Question

Solve
-13x^3 +118x +360=0​

Answer 1

Answer:

$- 13 {x}^{3} + 118x + 360 = 0 \\ - 13 {x}^{3} + 52 {x}^{2} - 52 {x}^{2} + 208x - 90x + 360 = 0 \\ - 13 {x}^{2} (x - 4) - 52x (x - 4) - 90x(x - 4) = 0\\ (x - 4)( - 13 {x}^{2} - 52x - 90) = 0 \\ either \: x - 4 = 0 \\ then \: x = 4 \\ either \: - 13 {x}^{2} - 52x - 90 = 0 \\ \: \: \: \: \: 13 {x}^{2} + 52x + 90 = 0 \\ by \: quadratic \: formua \: \\ x = \frac{ - 52 + \sqrt{ {52}^{2} - 4 \times 13 \times 90 } }{2 \times 13} \\ x = \frac{ - 52 + \sqrt{ {52}^{2} - 4 \times 13 \times 90 } }{2 \times 13} \\ x = \frac{ - 52 + \sqrt{ - 1976} }{26} \\ x = \frac{ - 52 + 44i}{26} \\ \\ and \: similarly \: \\ x = \frac{ - 52 - 44i}{26}$

I hope everything will be clear if any doubts ask me in comments