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a) 13 + 87 : 100
= (13 + 87) : 100
= 100 : 100
= 1
b) 30 + 12 + 70 + 88
= (30 + 70) + (12 + 88)
= 100 + 100
= 200
c) 55 + 44 + 45
= (55 + 45) + 44
= 100 + 44
= 144
c) 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= (1 + 9) + (2 + 8) + (3 + 7) + (4 + 6) + 5
= 10 + 10 + 10 + 10 + 5
= 40 + 5
= 45
a ) 1
b ) 30 + 12 + 70 + 88
= ( 30 + 70 ) + ( 88 + 13 )
= 100 + 100
= 200
c ) 55 + 44 + 45
= ( 55 + 45 ) + 44
= 100 + 44
= 144
d ) 1+2+3+4+5+6+7+8+9
= ( 1+9 ) + ( 2+8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5
= 10 + 10 + 10 + 10 + 5
= 45
\(\frac{5}{1\cdot6}+\frac{5}{6\cdot11}+...+\frac{5}{101\cdot106}\)
\(=\frac{1}{1\cdot6}+\frac{1}{6\cdot11}+...+\frac{1}{101\cdot106}\)
\(=\frac{1}{1}-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+...+\frac{1}{101}-\frac{1}{106}\)
\(=\frac{1}{1}-\frac{1}{106}\)
\(=\frac{106}{106}-\frac{1}{106}\)
\(=\frac{105}{106}\)
Đề sai nha bn
\(B=\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{101.106}\)
\(B=\frac{6-1}{1.6}+\frac{11-6}{6.11}+...+\frac{106-101}{101.106}\)
\(B=1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+...+\frac{1}{101}-\frac{1}{106}\)
\(B=1-\frac{1}{106}=\frac{106}{106}-\frac{1}{106}=\frac{105}{106}\)
Vậy B = \(\frac{105}{106}\)
a) 46+17+54
=(46+54)+17
=100+17
=117
b) 4x37x25
=25x4x37
=100x37
=3700
c) 87x36+87x64
=87x(36+64)
=87x100
=8700
tk nhé
46 +17 + 54
= (46 + 54) + 17
= 100 + 17
= 117
4 x 37x.25
= (4 x 25) x 37
= 100 x 37
= 3700
87 x 36 + 87 x 64
= 87 x (36 + 64 )
= 87 x 100
= 8700
( 8 x - 12 ) ^ 3 = 125
( 8 x - 12 ) ^ 3 = 5 ^ 3
=> 8 x - 12 = 5
8 x = 17
x = \(\frac{17}{8}\)
a) 1 - 2 + 3 - 4 + 5 - 6 + 7 - 8 + 9 - 10 + 11
= (1 - 2) + (3 - 4) + (5 - 6) + (7 - 8) + (9 - 10) + 11
= -1 + (-1) + (-1) + (-1) + (-1) + 11
= -1 x 5 + 11
= -5 + 11
= 6
b) 98 + 87 + 76 + ... + 21 - 12 - 23 - 34 - ... - 89
= (98 89) + (87 - 78) + ... + (21 - 12) (có 8 nhóm)
= 9 + 9 + ... + 9 (có 8 số 9)
= 9 x 8
= 72
\(1-2+3-4+.....-10+11\)
\(=\left(1-2\right)+\left(3-4\right)+...\left(9-10\right)+11\)
\(=1+\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)+11\)
\(=-1\times5+11\)
\(=6\)
1+445+62+552-813
=446 +614-813
=1060 -813
=247 nha bạn