4 7 5
_ + _ + _ =
15 21 24
Tìm số tận cùng của A=2425_3316+195_7721+185+20152014
\(A=24^{25}-33^{16}+19^5-77^{21}+18^5+2015^{2014}\)
A= ....4 - ....1 + ...9 - ...7 + ...8 +...5
A= ...3 + ...9 -...7 + ... 8 + ...5
A= .....5 +.....8 +....5
A= ...8
=> Vậy A có tận cùng là 8
4/15 + 7/21 + 5/24
a, 5*18*4/3*4*25
b, 15*24*7/5*16*21
\(24\times5^5_{ }+5^2\times5^3\)
`24 xx 5^5 + 5^2 xx 5^3`
`=24 xx 5^5 + 5^5`
`=5^5 (24 +1)`
`=5^5 . 25`
`=5^5 .5^2`
`=5^7`
=24x3125 +\(5^2+5^3\)
=75000+ \(5^5\)
=75000+3125
=78125
\(24\cdot5^5+5^2\cdot5^3\)
\(=24\cdot5^5+5^5\)
\(=5^5\cdot5^2=5^7\)
bài 3: Tính:
1) 1/6 - -5/6 2) 6/13 - -14/39 3) 4/5 - 4/-18 4) 7/21 - 9/-36
5) -12/18 - -21/35 6) -3/21 - 6/42 7) -18/24 - 15/21 8) 1/6 - 2/5
các bn giup mik mik vs
1)1/6 - - 5/6 = 1/6 + 5/6 = 1
2)6/13 - -14/39 = 6/13 + 14/39= 32/39
3)4/5 - 4/-18 = 4/5 + 4/18= 46/45
4)7/21 - 9/-36 = 7/21 + 9/36 = 7/12
5)-12/18 - -21/35 = -12/18 + 21/35 = -1/15
6)-3/21 - 6/42 = -2/7
7)-18/24 - 15/21 = -41/28
8)1/6 - 2/5 =-7/30
(-9/10-15/16).(5/12-11/15-7/20)
5/14.1/3.-4/15:5/7
-3/5+28/5.(43/56+5/24-21/63)
T=(7/12+4/21+2/24+11/30+3/40+15/56) - (2/3+2/4+2/5)
Tính:
a) 16/15 . -5/14 . 54/24 . 56/21
b)7/3 . -5/2 . 15/21 . 4/-5
c)( -2/5 + 1/3) . ( 3/2 - 3/7)
d)(1/2 - 1/3) . ( 5 - 1/4)
e) ( 4/5)^2
a: \(\dfrac{16}{15}\cdot\dfrac{-5}{14}\cdot\dfrac{54}{24}\cdot\dfrac{56}{21}\)
\(=\dfrac{16}{24}\cdot\dfrac{-5}{15}\cdot\dfrac{54}{21}\cdot\dfrac{56}{14}\)
\(=\dfrac{2}{3}\cdot\dfrac{-1}{3}\cdot\dfrac{18}{7}\cdot4\)
\(=\dfrac{-2\cdot2\cdot4}{7}=-\dfrac{16}{7}\)
b: \(\dfrac{7}{3}\cdot\dfrac{-5}{2}\cdot\dfrac{15}{21}\cdot\dfrac{4}{-5}\)
\(=\dfrac{7}{3}\cdot\dfrac{5}{7}\cdot\dfrac{5}{2}\cdot\dfrac{4}{5}\)
\(=\dfrac{5}{3}\cdot\dfrac{4}{2}=\dfrac{5}{3}\cdot2=\dfrac{10}{3}\)
c: \(\left(-\dfrac{2}{5}+\dfrac{1}{3}\right)\left(\dfrac{3}{2}-\dfrac{3}{7}\right)\)
\(=\dfrac{-2\cdot5+3}{15}\cdot\dfrac{3\cdot7-3\cdot2}{14}\)
\(=\dfrac{-7}{15}\cdot\dfrac{15}{14}=\dfrac{-7}{14}=-\dfrac{1}{2}\)
d: \(\left(\dfrac{1}{2}-\dfrac{1}{3}\right)\left(5-\dfrac{1}{4}\right)\)
\(=\dfrac{3-2}{6}\cdot\dfrac{20-1}{4}\)
\(=\dfrac{1}{6}\cdot\dfrac{19}{4}=\dfrac{19}{24}\)
e: \(\left(\dfrac{4}{5}\right)^2=\dfrac{4^2}{5^2}=\dfrac{16}{25}\)
Tính T = (7/12 +4/21+2/24+11/30+15/56 _ - (2/3 -2/4+2/5)