Question

x²-9x-2=0 find x²+4/x²​

Answer 1

Step-by-step explanation:

${x}^{2} - 9x + 2 = 0 \\ \\ \\ \\ d = {9}^{2} - 4( - 2)(1) \\ = 81 + 8 \\ = 90 \\ \\ \\ x = \frac{ 9 + \sqrt{90} }{2} \: \: \: \: \: \: or \: \: \: \: x = \frac{ 9 - \sqrt{90} }{2} \\ \\multiplying \: \: these \: two \: equations \\ \\ {x}^{2} = \frac{81 - 90}{4} \\ \\ {x}^{2} = \frac{ - 9}{4} \\ \\ {x}^{2} = - \frac{9}{4} \\ \\ \\ {x}^{2} + \frac{4}{ {x}^{2} } = - \frac{9}{4} + 4( \frac{ - 4}{9} ) = \frac{ - 81 - 64}{ 36} \\ \\ = \frac{ - 145}{ 36}$