化简 5/(14m^5+28m^4-42m^3)-2/(7m^3-7m^2)

解答

化简

\frac{5}{14 m ^{5} + 28 m ^{4} - 42 m ^{3}} - \frac{2}{7 m ^{3} - 7 m ^{2}}

\frac{5 - 4 m ^{2} - 12 m}{14 m ^{3} ( m - 1 ) ( m + 3 )}

求解步骤

\frac{5}{14 m ^{5} + 28 m ^{4} - 42 m ^{3}} - \frac{2}{7 m ^{3} - 7 m ^{2}}

14 m^{5} + 28 m^{4} - 42 m^{3}, 7 m^{3} - 7 m^{2}

的最小公倍数:

14 m^{3} (m - 1) (m + 3)

根据最小公倍数调整分式

= \frac{5}{14 m ^{3} ( m - 1 ) ( m + 3 )} - \frac{4 m ( m + 3 )}{14 m ^{3} ( m - 1 ) ( m + 3 )}

使用分式法则:

\frac{a}{c} - \frac{b}{c} = \frac{a - b}{c}

= \frac{5 - 4 m ( m + 3 )}{14 m ^{3} ( m - 1 ) ( m + 3 )}

化简

5 - 4 m (m + 3) : 5 - 4 m^{2} - 12 m

= \frac{5 - 4 m ^{2} - 12 m}{14 m ^{3} ( m - 1 ) ( m + 3 )}

3 x - 91 > - 87 or 21 x - 17 > 25

\frac{x + 6}{3} - x + 6 \leq \frac{x}{15}

3 (2 x - 9) - 4 x > - (x + 9)

s im pl i f y - \frac{5}{6} + \frac{2}{9} + \frac{7}{18}

s im pl i f y \frac{π ^{3}}{0.00012}