Akar-akar persamaan ku adrat dari X2-8X-40=0

[tex]x = \frac{ - ( - 8) \sqrt{( { - 8}) ^{2} - 4 \times 1 \times ( - 40) } }{2 \times 1} \\ x = \frac{8 \sqrt{224} }{2} \\ x = \frac{8 + 4 \sqrt{14} }{2} \\ x = \frac{8 - 4 \sqrt{14} }{2} \\ x1 = 4 - 2 \sqrt{14} \\ x2 = 4 + 2 \sqrt{14} [/tex]