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a, ( x - 21 x 13 ) : 11 = 39 Tich mk cau b) ti nua mk lam cho gio phai di hoc them rui
x - 273 = 39 x 11
x - 273 = 429
x = 429 + 273
x = 702
a, ( x - 21 x 13 ) : 11 = 39 b, ( x - 21 ) x 13 : 11 = 39
( x - 21 x 13 ) = 39 x 11 ( x - 21 ) x 13 = 39 x 11
( x - 21 x 13 ) = 429 ( x - 21) x 13 = 429
x - 273 = 429 ( x - 21 ) = 429 : 13
x = 429 + 273 ( x - 21 ) = 33
x = 702 x = 33 + 21
x = 54
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a) ( x -21 * 13) : 11 = 39 => x - 21*13 = 39 * 11 => x - 273 = 429 => x= 429 + 273 => x= 702 b) ( x - 21) * 13 : 11 = 39 => (x-21)*13=39:11 => (x-21)*13=429 => x-21=429:13 => x-21=33 => x=33+21 => x=54
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5B = 1/11 - 1/16 + 1/16 - 1/21 + 1/21 - 1/26 +.........+ 1/56 - 1/61 +1/61 - 1/66
5B = 1/11 - 1/66
5B = 5/66
B = 1/66
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a) 2115 : x = 21
=> x = 2115 : 21 = \(\frac{705}{7}\) ( sai đề )
b) \(\left(9\times x-21\right):3=2\)
=> \(\left(9\times x-21\right)=2\times3=6\)
=> \(9\times x=6+21=27\)
=> \(x=27:9=3\)
Vậy x = 3
c) 231 + ( 312 - x ) = 531
=> 231 + 312 - x = 531
=>. 543 - x = 531
=> x = 543 - 531 = 12
Vậy x = 12
a) 2115 : x = 21
x= 705/7
b) ( 9 * x - 21) : 3 = 2
9 * x - 21 = 6
9 * x = 27
x = 3
c) 231 + ( 312 - x) = 531
231 + 312 - x = 531
543 - x = 531
x =12
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a) 53.39 + 47.39 - 53.21 - 47.21
= 53.(39 - 21) + 47.(39 - 21)
= 53.18 + 47.18
= 18.(53 + 47)
= 18.100
= 1800
b) = ( 2 x 12 ) x 53 + ( 4 x 6 ) x 87 - ( 3 x 8 ) x 40
= 24 x 53 + 24 x 87 - 24 x 40
= 24 x ( 53 + 87 - 40 )
= 24 x 100
= 2400
Chúc bạn học tốt :3
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\(A=\frac{9}{15.18}+\frac{9}{18.21}+.....+\frac{9}{89.92}\)
\(A=3.\left(\frac{3}{15.18}+\frac{3}{18.21}+....+\frac{3}{89.92}\right)\)
\(A=3.\left(\frac{1}{15}-\frac{1}{18}+\frac{1}{18}-\frac{1}{21}+......+\frac{1}{89}-\frac{1}{92}\right)\)
\(A=3.\left(\frac{1}{15}-\frac{1}{92}\right)\)
\(A=3.\frac{77}{1380}=\frac{77}{460}\)
A=915.18+918.21+.....+989.92A=915.18+918.21+.....+989.92
A=3.(315.18+318.21+....+389.92)A=3.(315.18+318.21+....+389.92)
A=3.(115−118+118−121+......+189−192)A=3.(115−118+118−121+......+189−192)
A=3.(115−192)A=3.(115−192)
A=3.771380=77460
X x 21 - 684,37 = 669,71
X x 21 = 669,71 + 684,37
X x 21 = 1354,08
X = 1354,08 : 21
X = 64,48
Trl :
X x 21 - 684,37 = 669,71
X x 21 = 669,71 + 684,37
X x 21 = 1354,08
X = 1354,08 : 21
X = 64,48