Rút gọn phân số :

a) \(\dfrac{85-17+34}{51-102}\)

\(=\dfrac{102}{-51}=-2\)

b) \(\dfrac{-13.6+12.5}{6\left(-7\right)-\left(-4\right).6}\)

\(=\dfrac{-78+60}{6\left[\left(-7\right)-\left(-4\right)\right]}\)

\(=\dfrac{-18}{-18}=1\)

c) \(\dfrac{2^4.5^2.7}{2^3.5.7^2.11}\)

\(=\dfrac{2^4}{2^3}.\dfrac{5^2}{5}.\dfrac{7}{7^2}.11\)

\(=2.5.\dfrac{1}{7}.11\)

\(=15\dfrac{5}{7}=\dfrac{110}{7}\)

Bài 1: rút gọn phân số

a ) 2.7.13 phần 26.35

b) 31.7-31 phần 4-35

c) 32.7-32.4 phần 38-35

d) 1717-101 phần 2828+202

e ) 3.6+2.9.5-18.(-4) phần 7.(-7)+12.(-7)+7

Giúp mình với mình đag cần cho sáng mai

a) \(\dfrac{2\cdot7\cdot13}{26\cdot35}=\dfrac{2\cdot7\cdot13}{2\cdot13\cdot5\cdot7}=\dfrac{1}{5}\)

b) \(\dfrac{31\cdot7-13}{4-35}=\dfrac{217-13}{-31}=\dfrac{-204}{31}\)

c) \(\dfrac{32\cdot7-32\cdot4}{38-35}=\dfrac{32\cdot\left(7-4\right)}{3}=\dfrac{32\cdot3}{3}=32\)

d) \(\dfrac{1717-101}{2828+202}=\dfrac{1616}{3030}=\dfrac{8}{15}\)

e) \(\dfrac{3\cdot6+2\cdot9\cdot5-18\cdot\left(-4\right)}{7\cdot\left(-7\right)+12\cdot\left(-7\right)+7}\)

\(=\dfrac{18+18\cdot5+18\cdot4}{7\cdot\left(-7\right)-12\cdot7+7}\)

\(=\dfrac{18\cdot\left(1+5+4\right)}{7\cdot\left(-7-12+1\right)}\)

\(=\dfrac{18\cdot10}{7\cdot\left(-18\right)}\)

\(=\dfrac{-10}{7}\)