Question

сократить дробь х^2-18х+81 черта дроби 81-х^2

Answer 1

$\frac{ {x}^{2} - 18x + 81}{81 - {x}^{2} } = \frac{(x - 9) {}^{2} }{(9 - x)(9 + x)} = \frac{( x- 9)(x - 9)}{ - (x - 9)(x + 9)} = - \frac{x - 9}{x + 9}$