\[ (x-4)^2 = x^2 - 8x + 16 \]
\[ (x+9)^2 = x^2 + 18x + 81 \]
\[ x^2 - 8x + 16 + x^2 + 18x + 81 = 2x^2 \]
\[ 2x^2 + 10x + 97 = 2x^2 \]
\[ 10x + 97 = 0 \]
\[ 10x = -97 \]
\[ x = - \frac{97}{10} \]
Ответ: -9.7