Question

объясните пожалуйста,как получилось 9/25?​

Answer 1

$1-\frac{v^2}{9*10^{10}}=\frac{16}{25}<=>-\frac{v^2}{9*10^{10}}=\frac{16}{25}-1<=>\\<=>-\frac{v^2}{9*10^{10}}=-\frac{9}{25}<=>\frac{v^2}{9*10^{10}} =\frac{9}{25}$

Answer 2

$1-\frac{v^2}{9\cdot 10^{10}}=\frac{16}{25}\\\\\frac{v^2}{9\cdot 10^{10}}=1-\frac{16}{25}\\\\\frac{v^2}{9\cdot 10^{10}}=\frac{25}{25}-\frac{16}{25}\\\\\frac{v^2}{9\cdot 10^{10}}=\frac{25-16}{25}\\\\\frac{v^2}{9\cdot 10^{10}}=\frac{9}{25}$

$v^2=\frac{9\cdot 9\cdot 10^{10}}{25}\\\\v=\pm \sqrt{\frac{9^2\cdot (10^5)^2}{5^2}}\\\\v=\pm \frac{9\cdot 10^5}{5}\\\\v=\pm 180000$