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2 ) B = \(1\frac{6}{41}.\left(\frac{12+\frac{12}{19}-\frac{12}{37}-\frac{12}{53}}{3+\frac{3}{19}-\frac{3}{37}-\frac{3}{53}}:\frac{4+\frac{4}{17}+\frac{4}{19}+\frac{4}{2006}}{5+\frac{5}{17}+\frac{5}{19}+\frac{5}{2006}}\right).\frac{124242423}{237373735}\)
B = 47/41 . ( 12/3 : 4/5 ) . 123/235
B = 47/41 . ( 4 : 4/5 ) . 123/235
B = 47/41 . 5 . 123/235
B = \(\frac{47.5.123}{41.235}\)
B = 3
1 ) A = \(\frac{636363.37-373737.63}{1+2+3+...+2006}\)
A = \(\frac{63.10101.37-37.10101.63}{1+2+3+...+2006}\)
A = \(\frac{0}{1+2+3+...+2006}\)
A = 0
1/29(19-13) - 19(29-13)
=29.19-29.13 - 19.29+19.13
=(29.19-19.29)-(29.13-19.13)
=0-13.(29-19)
=-13.10
=-130
2/ 31.(-18)+31.(-81)-31
= 31.( -18 - 81 - 1)
= 31.(-100)
= -3100
số sh cua tong A bang so hang cua day so cach deu 1 don vi tu 1 den 60
so sh cua tong A la:(60-1):1+1=60 (sh)
Cu 3 sh lien tiep cua tong A nhom thanh 1 nhom thi ta duoc so nhom la : 60: 3=20(nhom)
khi do : A = (2+2^2+2^3)+(2^4+2^5+2^6)+(2^7+2^8+2^9)+....+(2^58+2^59+2^60)
A=(2+2.2+2.2^2)+(2^4+2^4.2+2^4.2^2)+(2^7+2^7.2+2^7.2^2)+.....+(2^58
2^58.2+2^58.2^2)
A=2(1+2+2^2)+2^4(1+2+2^2)+2^7(1+2+2^2)+...+2^58(1+2+2^2)
A=2.7+2^4.7+2^7.7+...+2^58.7
A=7(2+2^4+2^7+...+2^58)
Vi 7 chia het cho 7
2+2^4+2^7+...+2^58 thuoc N
Suy ra 7(2+2^4+2^7+...+2^58) chia het cho 7
hay A chia het cho 7
Vay A chia het cho 7
Câu 1:
abc >/ 100 ; bca >/ 100 ; cab>/100
< = > abc + bca + cab >/300
< = > abc + bca + cab >/ 111
\(\frac{\frac{2}{33}+\frac{2}{25}+\frac{2}{19}}{\frac{3}{33}+\frac{3}{25}+\frac{3}{19}}=\frac{2\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}{3\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}=\frac{2}{3}\)
= \(\frac{2\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}{3\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}=\frac{2}{3}\)
a ) số đối : -9 = 9 ; 17 = 17
b ) 63 = 216 ; 70 = 1
Bài 2 :
a) 42
b) 30
c) 3800
Bài 3 :
a) x = -31
b) x = 2
c) x = { -2 ;-1 ; 0 ;1;2;3;4 }
1/a.9;-17.
b.216;1
2/a.42;b.30;c.3800
3/a.x=-31;b.x=2;c.x=-2;-1;0;1;2;3;4.
\(=81.53+19.\left(28+25\right)\)
\(=81.53+19.53\)
\(=\left(81+19\right).53\)
\(=100.53\)
\(=5300\)
81*53+19*28+19*25
=81*53+19*(28+25)
=81*53+19*53
=53*(81+19)
=53*100
=5300