Question

Умоляю пж алгебра
Вот:

Answer 1

$\displaystyle\bf\\\frac{49^{2} -21^{2} }{57^{2}-15^{2} }=\frac{(49-21)(49+21)}{(57-15)(57+15)}=\frac{28\cdot 70}{42\cdot 72} =\frac{4\cdot 7\cdot 7\cdot 2\cdot 5}{6\cdot 7\cdot 8\cdot 9} =\\\\\\=\frac{7\cdot 5}{6\cdot 9} =\frac{35}{54} \\\\\\\frac{35}{54} \cdot 27=\frac{35\cdot27}{2\cdot27} =\frac{35}{2} =\boxed{17,5}$