rút gọn phân số:
1, -1997.1996+1 / (-1995).(-1997)+1996
2, 2.3+4.6+14.21 / 3.5+6.10+21.35
3, 3.7.13.37.39-10101 / 505050 - 70707
4, 18.34+(-18).124 / -36.17+9.(-52)
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10 tháng 6 2017
a) \(\frac{2929-101}{2.1919+404}\)\(=\frac{101.29-101}{2.1919+2.202}\)\(=\frac{101\left(29-1\right)}{2\left(1919+202\right)}\)\(=\frac{101.28}{2.2121}\)\(=\frac{2.101.7.2}{2.101.7.3}\)\(=\frac{2}{3}\)
b) \(\frac{-1997.1996+1}{-1995\left(-1997\right)+1996}\)\(=\frac{-1997.\left(1995+1\right)+1}{-1995\left(-1997\right)+1996}\)\(=\frac{-1997.1995-1997+1}{-1\left(-1997\right).1995+1996}\)\(=\frac{-1997.1995-1996}{1997.1995+1996}\)\(=\frac{-\left(1997.1995+1996\right)}{1997.1995+1996}\)\(=-1\)
c) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)\(=\frac{2.3+4.2.3+2.7.3.7}{3.5+2.3.2.5+3.7.5.7}\)\(=\frac{2.3\left(1+4+7.7\right)}{3.5\left(1+2.2+7.7\right)}\)\(=\frac{2\left(1+4+49\right)}{5\left(1+4+49\right)}\)\(=\frac{2}{5}\)
d) \(\frac{3.7.13.37.39-10101}{505050-70707}\)\(=\frac{3.7.13.37.39-3.7.13.37}{2.3.5.5.7.13.37-3.7.7.13.37}\)\(=\frac{3.7.13.37\left(39-1\right)}{3.7.13.37\left(2.5.5-7\right)}\)\(=\frac{38}{43}\)
e) \(\frac{18.34+\left(-18\right).124}{-36.17+9.\left(-52\right)}\)\(=\frac{18.2.17-18.2.62}{\left(-1\right).2.2.3.3.17+\left(-1\right)2.2.3.3.13}\)\(=\frac{18.2\left(17-62\right)}{\left(-1\right).2.2.3.3\left(17+13\right)}\)\(=\frac{\left(-1\right).2.2.3.3.45}{\left(-1\right).2.2.3.3.30}\)\(=\frac{45}{30}\)\(=\frac{3}{2}\)
NN
19 tháng 4 2017
a, \(\dfrac{25.13}{26.35}=\dfrac{5.1}{2.7}=\dfrac{5}{14}.\)
b, \(\dfrac{6.9-2.17}{63.3-119}=\dfrac{2.3.9-2.17}{9.7.3-17.7}=\dfrac{2\left(3.9-17\right)}{7\left(9.3-17\right)}=\dfrac{2}{7}.\)
c, \(\dfrac{3.13-13.18}{15.40-80}=\dfrac{13\left(3-18\right)}{15.40-40.2}=\dfrac{13.\left(-15\right)}{40\left(15-2\right)}=\dfrac{13.\left(-15\right)}{40.13}=\dfrac{-15}{40}=\dfrac{-3}{8}.\)d, \(\dfrac{2929-101}{2.1919+404}=\dfrac{29.101-101.1}{2.19.101+101.4}=\dfrac{101\left(29-1\right)}{38.101+101.4}=\dfrac{101\left(29-1\right)}{101\left(38+4\right)}=\dfrac{29-1}{38+4}=\dfrac{28}{42}=\dfrac{2}{3}.\)
(còn tiếp!!!)
~ Chúc bn học tốt!!! ~
12 tháng 5 2017
a)\(\dfrac{3.7.13.37.39-10101}{505050-70707}\)=\(\dfrac{10101.39-10101}{10101.50-10101.7}\)=\(\dfrac{10101.\left(39-1\right)}{10101.\left(50-7\right)}\)=\(\dfrac{39-1}{50-7}\)=\(\dfrac{38}{43}\)
b)\(\dfrac{18.34+\left(-18\right).124}{-36.17+9.\left(-52\right)}\)=\(\dfrac{36.17+36.\left(-62\right)}{36.\left(-17\right)+36.\left(-13\right)}\)=
\(\dfrac{36.\left[17+\left(-62\right)\right]}{36.\left[\left(-17\right)+\left(-13\right)\right]}\)=\(\dfrac{36.\left(-45\right)}{36.\left(-20\right)}\)=\(\dfrac{45}{20}\)=\(\dfrac{9}{4}\)=2\(\dfrac{1}{4}\)
25 tháng 4 2016
Phân số a quá dễ, bạn chỉ việc giản ước tử với mẫu sẽ được \(\frac{1}{-1995}\)
25 tháng 4 2016
b) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)
Sau khi giản ước ta có:
\(\frac{2+2+2}{5+5+5}=\frac{8}{15}\)
=-1
=2/5
=38/43
= 3/2