Question

Сократить дробь а^2-16а+63/а^2-81

Answer 1

$frac{a^2-16a+63}{a^2-81} = frac{a^2-7a+9a+63}{(a-9)(a+9)} = frac{a(a-7)-9(a-7)}{(a-9)(a+9)} = frac{(a-9)(a-7)}{(a-9)(a+9)} = frac{a-7}{a+9}$