Question

resolva a equaçao x2-8x+20=0

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Answer 1

${x }^{2} - 8x + 20 = 0 \\ \\ delta = {b}^{2} - 4ac \\ delta = ( - 8 {)}^{2} - 4 \times 1 \times 20 \\ delta = 64 - 80 \\ delta = - 16 \\ \sqrt{delta} = \sqrt{ - 16} = \sqrt{ 16} \times \sqrt{ - 1} \\ \sqrt{delta} = 4i \\ \\ x_1 = \frac{ - b + \sqrt{delta} }{2a} = \frac{ - ( - 8) + 4i}{2 \times 1} \\ x_1 = \frac{8 + 4i}{2} \\ \boxed{x_1 = 4 + 2i} \rightarrow \: \boxed{x_2 = 4 - 2i}$