Question

0.81x²-1=0
Найдите корень уравнения
Срочно!!!!
50балл​

Answer 1

$0.81x {}^{2} - 1 = 0 \\ \frac{81}{100} x {}^{2} - 1 = 0 \\ 81x {}^{2} - 100 = 0 \\ 81x {}^{2} = 100 \\ x {}^{2} = \frac{100}{81} \\ x = ± \frac{10}{9} \\ x1 = - \frac{10}{9} ;⠀⠀x2 = \frac{10}{9}$