Question

допоможіть зробити 2 випадки будь ласка!​

Answer 1

$1)\ \ a-\dfrac{1}{a}=9\\\\\Big(a-\dfrac{1}{a}\Big)^2=9^2\\\\a^2-2+\dfrac{1}{a^2}=81\\\\a^2+\dfrac{1}{a^2}=81+2\\\\a^2+\dfrac{1}{a^2}=83$

$2)\ \ a^2+\dfrac{1}{a^2}=6\\\\\\\Big(a-\dfrac{1}{a}\Big)^2=a^2-2+\dfrac{1}{a^2}=\Big(a^2+\dfrac{1}{a^2}\Big)-2=6-2=4\\\\\\a-\dfrac{1}{a}=\pm 2$