Question

решите 1,3 уравнения

Answer 1

$1) \: \: {x}^{2} - 25 = 0 \\ {x}^{2} = 25 \\ x = + - \sqrt{25} \\ x = + - 5 \\ 2) \: \: {x}^{2} - 10x + 21 = 0 \\ x1 + x2 = 10 \\ x1 \times x2 = 21 \\ x1 = 7 \\ x2 = 3$