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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) \(\dfrac{3\cdot6+2\cdot9\cdot5-18\cdot\left(-4\right)}{7\cdot\left(-7\right)+12\cdot\left(-7\right)+7}\)
\(=\dfrac{18+18\cdot5+18\cdot4}{7\cdot\left(-7\right)-12\cdot7+7}\)
\(=\dfrac{18\cdot\left(1+5+4\right)}{7\cdot\left(-7-12+1\right)}\)
\(=\dfrac{18\cdot10}{7\cdot\left(-18\right)}\)
\(=\dfrac{-10}{7}\)
1,rút gọn
a,21.30-15 phần 35.50-25
b,17.17-101 phần 28.28+404
c,3.6+2.9.5-18.(-4) phần 7.(-7)+12.(-7)+7
a) − 7 .3 + 4. − 6 − 5 .3 + 2.3 = − 45 = 9 = 6
b) 3.6 + 2.9.5 − 18. − 4 7. − 7 + 12. − 7 + 7 = 18. 1 + 5 + 4 − 7 . 7 + 12 − 1 = 18.10 − 7.18 = − 10 7
\(\frac{3.6+2.9.5-18.\left(-4\right)}{7.\left(-7\right)+12.\left(-7\right)+7}=\frac{18+18.5-18.\left(-4\right)}{\left(-7\right).\left(7+12\right)+7}\)
\(=\frac{18\left[1+5-\left(-4\right)\right]}{\left(-7\right).19+7}=\frac{18.10}{7.\left(-19\right)+7}\)
\(=\frac{180}{7\left[\left(-19\right)+1\right]}=\frac{180}{-126}=\frac{=10}{7}\)
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) \(\dfrac{2^4.5^2.7}{2^3.5.7^2.11}\)
\(=\dfrac{2^4}{2^3}.\dfrac{5^2}{5}.\dfrac{7}{7^2}.11\)
\(=2.5.\dfrac{1}{7}.11\)
\(=15\dfrac{5}{7}=\dfrac{110}{7}\)