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, \(\frac{3.7.13.37.39-10101}{505050-70707}=\frac{10101.39-10101}{50.10101-7.10101}\)
\(=\frac{10101.\left(39-1\right)}{10101.\left(50-7\right)}\)
\(=\frac{10101.38}{10101.43}\)
\(=\frac{38}{43}\)
Rút gọn phân số :
a)\(\frac{6.9-2.17}{6.3-11.9}\)
b)\(\frac{3.13-13.18}{15.40-80}\)
c)\(\frac{\left(-5\right)^3.40.43}{135.\left(-2\right)^{14}.\left(-100\right)^0}\)
d)\(\frac{2929-101}{2.1919+404}\)
Can you help me ?
rút gọn phân số:
1, 3.13-13.18 / 15.40-80
2, (-5)^3.40. 4^3 / 135.(-2)^14.(-100)^0
3, 2929-101 / 2.1919+404
Đặt A = \(\frac{3.13-13.18}{15.40-80}\)
=> A = \(\frac{13.\left(3-18\right)}{15.40-80}\)
=> A = \(\frac{13.\left(-15\right)}{15.40-40.2}\)
=> A = \(\frac{13.\left(-15\right)}{40.\left(15-2\right)}\)
=> A = \(\frac{13.\left(-15\right)}{40.13}\)
=> A = \(\frac{-15}{40}\)
=> A = \(\frac{-3}{8}\)
Rút gọn phân số
\(y=\frac{\left(-5\right)^3.40.4^3}{135.\left(-2\right)^{14}.1}\) ; \(\frac{2929-101}{2.1919+404}\) ; \(\frac{-1997.1996+1}{-1995.\left(-1997\right)+1996}\)
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)\(\frac{18.34+\left(-18\right).124}{-36.17+9.\left(-52\right)}\)
\(\frac{13.\left[2929-101\right]}{2.1919+404}\)
Rút gọn phân số trên.
\(\frac{13.\left(2929-101\right)}{2.1919+404}=\frac{13\left(101.29-101\right)}{2.101.19+101.4}=\frac{13.101\left(29-1\right)}{2.101\left(19+2\right)}=\frac{13.28}{2.21}=\frac{13.2}{3}=\frac{26}{3}\)
Rút gọn \(\frac{2929-101}{2.1919+404}\)
\(\frac{101.29-101.1}{2.101.19+101.4}\)
\(=\frac{101.\left(29-1\right)}{101.\left(2.19+4\right)}\)
\(=\frac{28}{38+4}\)
\(=\frac{28}{42}=\frac{2}{3}\)
Rút gọn :
A = \(\frac{4116-14}{10290-35}\)
B = \(\frac{2929-101}{2.1919+404}\)
CHÚNG TỎ RẰNG :
\(\frac{1}{101}+\frac{1}{102}+\frac{1}{103}+..........+\frac{1}{149}+\frac{1}{150}>\frac{1}{3}\)
Ta thấy 1/101>1/150 ; 1/102>1/150 ; .... ; 1/149>1/150 ; 1/150=1/150
suy ra 1/101+1/102+1/103+.....+1/149+1/150>50.1/150
1/101+1/102+1/103+.....+1/148+1/150>1/3
