率计算公式
率计算公式
\displaystyle \frac{a}{b}=\frac{c}{d}\Rightarrow ad=bc\\{}\\ \Rightarrow a=\frac{bc}{d};\ b=\frac{ad}{c};\\{}\\ \frac{a}{c}=\frac{b}{d};\ \frac{d}{b}=\frac{c}{a};\ \frac{d}{c}=\frac{b}{a};\\{}\\ \frac{a\pm b}{b}=\frac{c\pm d}{d};\\{}\\ \frac{a+b}{a-b}=\frac{c+d}{c-d};\\{}\\ \frac{a\pm b}{a}=\frac{c\pm d}{c};\\{}\\ \frac{a}{a\pm b}=\frac{c}{c\pm d};\\{}\\ \frac{b}{a\pm b}=\frac{d}{c\pm d}