Question

Найди X1^2-x2^2
если x1 и х2 корни уравнения х^2-8x+3=0​

Answer 1

${x}^{2} - 8x + 3 = 0 \\ d = {8}^{2} - 4 \times 3 = 64 - 12 = 52 \\ x = \frac{8 - \sqrt{52} }{2} = \frac{8 - 2 \sqrt{13} }{2} = 4 - \sqrt{13} \\ x = \frac{8 + \sqrt{52} }{2} = \frac{8 + 2 \sqrt{13} }{2} = 4 + \sqrt{13}$

${x1}^{2} - {x2}^{2} = {(4 + \sqrt{13} )}^{2} - {(4 - \sqrt{13} )}^{2} = \\ 16 + 8 \sqrt{13} + 13 - (16 - 8 \sqrt{13} + 13 ) = \\ 16 + 8 \sqrt{13} + 13 - 16 + 8 \sqrt{13} - 13 = \\ 8 \sqrt{13} + 8 \sqrt{13} = 16 \sqrt{13}$