Rút gọn phân số
1\(\frac{6.9-2.17}{63.3-119}\)
2) \(\frac{2929-101}{2.1919+404}\)
3) \(\frac{-1997.1996+1}{\left(-1995\right).\left(-1997\right)+1996}\)
4) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)
5) \(\frac{3.7.13.37.39+10101}{505050-707070}\)
Rút gọn phân số:
a/ 25.13/26.35
b/ 6.9 - 2.17/63.3 - 119
c/ 3.13 - 13.18/15.40 - 80
d/ 2929 - 101/2.1919 + 404
f/ -1997.1996+1/(-1995).(-1997)+1996
g/ 2.3+4.6+14.21/ 3.5+6.10+21.35
h/ 3.7.13.37.39 - 10101/ 505050 - 70707
/ dấu phân số
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!!!)
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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)
Rút gọn phân số:
a) \(\dfrac{2929-101}{2.1149+404}\)
b) \(\dfrac{6.9-2.17}{63.3-119}\)
c) \(\dfrac{3.13-13.18}{15.40-80}\)
d) \(\dfrac{-1997-1996+1}{\left(-1995\right).\left(-1997\right)+1996}\)
e) \(\dfrac{2.3+4.6+14.21}{3.5+6.10+21.35}\)
g) \(\dfrac{\left(-5\right)^3.40.4^3}{135.\left(-3\right)^{14}.\left(-100\right)^0}\)
h) \(\dfrac{18.34+\left(-18\right).124}{-36.17+9.\left(52\right)}\)
j) \(\dfrac{9.11+32.9}{23.15+12.23}\)
k) \(\dfrac{12.13+24.26+36.39}{24.26+48.52+72.78}\)
b) \(\dfrac{6\cdot9-2\cdot17}{63\cdot3-119}\)
\(=\dfrac{2\left(3\cdot9-17\right)}{7\cdot\left(3\cdot9-17\right)}\)
\(=\dfrac{2}{7}\)
Rút gọn các phân số sau
a,\(\frac{6.9-2.17}{63.3-119}\)b,\(\frac{3.13-13.18}{15.40-80}\) c,\(\frac{-1997.1996+1}{\left(-1995\right).\left(-1997\right)+1996}\)
d,\(\frac{3.7.13.37.39-10101}{505050-70707}\)
e,\(\frac{2929-101}{2.1919+404}\)
Trả lời:
a, \(\frac{6\times9-2\times17}{63\times3-119}=\frac{2.3\times9-2\times17}{7.9\times3-7.17}\)
\(=\frac{2\times\left(3\times9-17\right)}{7\times\left(3\times9-17\right)}\)
\(=\frac{2}{7}\)
b, \(\frac{3\times13-13\times18}{15\times40-80}=\frac{13\times\left(3-18\right)}{40\times\left(15-2\right)}\)
\(=\frac{13\times-15}{40\times13}\)
\(=\frac{-3}{8}\)
c, \(\frac{-1997.1996+1}{\left(-1995\right).\left(-1997\right)+1996}=\frac{-1997.1996+1}{\left(1-1996\right).\left(-1997\right)+1996}\)
\(=\frac{-1997.1996+1}{-1997-1996.\left(-1997\right)+1996}\)
\(=\frac{-1997.1996+1}{-1996.\left(-1997\right)-1}\)
\(=\frac{-1997.1996+1}{-\left[1996.\left(-1997\right)+1\right]}\)
\(=-1\)
d, \(\frac{3.7.13.37.39-10101}{505050-70707}=\frac{10101.39-10101}{50.10101-7.10101}\)
\(=\frac{10101.\left(39-1\right)}{10101.\left(50-7\right)}\)
\(=\frac{10101.38}{10101.43}\)
\(=\frac{38}{43}\)
a)\(\frac{-135}{540}\)
b)\(\frac{25.13}{26.35}\)
c)\(\frac{6.9-2.17}{63.3-119}\)
d)\(\frac{3.13-13.18}{15.40-80}\)
e)\(\frac{-5^3.40.4^4}{135.\left(-2\right)^{14}.\left(-100\right)^0}\)
f)\(\frac{2929-101}{2.1919+404}\)
g)\(\frac{-1997.1996+1}{\left(-1995\right).\left(-1997\right)+1996}\)
h)\(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)
i)\(\frac{3.7.13.37.39-10101}{505050-70707}\)
k)\(\frac{18.34+\left(-18\right).124}{-36.17+9.\left(-52\right)}\)
Rút gọn phân số
a) \(\frac{-1997.1996+1}{\left(-1995\right).\left(-1997\right)+1996}\) b) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)
c)\(\frac{3.7.13.37.39-10101}{505050-70707}\) d)\(\frac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}\left(-100\right)}\)
Phân số a quá dễ, bạn chỉ việc giản ước tử với mẫu sẽ được \(\frac{1}{-1995}\)
b) \(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)
Sau khi giản ước ta có:
\(\frac{2+2+2}{5+5+5}=\frac{8}{15}\)
\(\frac{-1997.1996+1}{\left(1996-1\right).1997+1996}=\frac{-1997.1996+1}{1996.1997-1997+1996}=\frac{-\left(1997.1996-1\right)}{1996.1997-1}=-1\)
\(\frac{2.3.\left(1+2.3+7.7\right)}{3.5.\left(1+3.2+7.7\right)}=\frac{2}{5}\)
\(\frac{3.7.13.37.39-10101}{505050-70707}=\frac{10101.39-10101}{10101.50-10101.7}=\frac{10101.\left(39-1\right)}{10101.\left(50-7\right)}=\frac{38}{43}\)
\(\frac{-5^3.2.2^6}{3^3.5.2^{14}.5}=\frac{-5^3.2^7}{3^3.5^2.2^{14}}=\frac{-5}{3^3.2^7}\)
Rút gọn phân số
\(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\) ; \(\frac{3.7.13.37.39-10101}{505050-70707}\) ; \(\frac{18.34+\left(-18\right).124}{-36.17+9.\left(-52\right)}\)
1.Tính tổng: \(\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+....+\frac{5}{99.101}\)
2.Rút gọn phân số:
a)\(\frac{2929-101}{2.1919+404}\) b)\(\frac{6.9-2.17}{63.3-119}\)
c)\(\frac{3.13-13.18}{15.40-80}\) d)\(\frac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}.\left(-100\right)^0}\)
e)\(\frac{-1997.1996+1}{-1995.\left(-1997\right)+1996}\) f)\(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\)
f)\(\frac{2.3+4.6+14.21}{3.5+6.10+21.35}\) g)\(\frac{3.7.13.37.39-10101}{505050-70707}\)
h)\(\frac{18.34+\left(-18\right).124}{-36.17+9.\left(-52\right)}\)
Bài 1:
Coi \(A=\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+....+\frac{5}{99.101}\)
\(2A=\left(\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+....+\frac{5}{99.101}\right).2\)
\(=5.\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+....+\frac{2}{99.101}\right)\)
\(=5.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{101}\right)\)
\(=5.\left(1-\frac{1}{101}\right)\)
\(=5.\frac{100}{101}\)
\(=\frac{500}{101}\Rightarrow A=\frac{500}{101}:2=\frac{250}{101}\)
\(\left(\frac{5}{1}-\frac{5}{3}+\frac{5}{3}-\frac{5}{5}....+\frac{5}{99}-\frac{5}{101}\right):\frac{1}{5}\)
\(\left(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}.....+\frac{1}{99}-\frac{1}{101}\right).5\)
\(\left(\frac{1}{1}-\frac{1}{101}\right).5\)
\(\frac{100}{101}.5\)
\(\frac{500}{101}\)
2,a,\(\frac{2929-101}{3838+404}\)\(=\frac{2828}{4242}=\frac{2}{3}\)
\(b,\frac{54-34}{189-119}=\frac{20}{70}=\frac{2}{7}\)
\(c,d,e,f,f,g,h\)\(tuong\) \(tu\)
\(\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+...............+\frac{5}{99.101}\)
\(=\frac{5.2}{1.3.2}+\frac{5.2}{3.5.2}+\frac{5.2}{5.7.2}+............+\frac{5.2}{99.101.2}\)
\(=\frac{5}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+.................+\frac{2}{99.101}\right)\)
\(=\frac{5}{2}.\left(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+.........+\frac{1}{99}-\frac{1}{101}\right)\)
\(=\frac{5}{2}.\left(1-\frac{1}{101}\right)\)
\(=\frac{5}{2}.\frac{100}{101}\)
\(=\frac{250}{101}\)
