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11 x 13 x 15 x 17 + 23 x 25 x 27 x 29 + 31 x 33 x 35 x 37 + 45 x 47 x 49 x 51
=7096860
#Hok tốt!#
\(\dfrac{11}{49}\times\dfrac{9}{1}\times\dfrac{7}{33}=\dfrac{11\times9\times7}{7\times7\times1\times11\times3}=\dfrac{9}{21}=\dfrac{3}{7}\)
1) x : 7 + 20 = 17 x 49 + 17 x 51
x : 7 +20 = 17 x ( 49+51)
x : 7 +20 =1700
x : 7 = 1700 - 20 =1680
x = 1680 x 7 =11 760
2) 287 - ( x+ 34) x 3 - 25 = 142
287-(x+34)x3 = 142 + 25 =167
( x+34) x 3 = 287 - 167=120
x + 34 = ``120 : 3 =40
x = 40 - 34 = 6
3)13x + 15x + 12x = 120
40x = 120
x = 120 : 40 = 3
A = 2 x 53 x 12 + 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
B = 5 x 7 x 77 - 7 x 60 + 49 x 25 - 15 x 42
= 5 x 7 x 77 - 7 x 5 x 12 + 49 x 5 x 5 - 5 x 3 x 42
= 5 x 539 - 84 x 5 + 245 x 5 - 5 x 126
= 5 x ( 539 - 84 + 245 - 126 )
= 5 x 574
= 2870
a=2×53×12+4×6×87-3×8×40
a=24×53+24×87-24×40
a=24×(53+87-40)
a=24×100
a=2400
\(\frac{7}{10}-\frac{3}{10}x\frac{1}{10}+\frac{4}{25}\)
\(=\frac{7}{10}-\frac{3}{100}+\frac{4}{25}\)
\(=\frac{70}{100}-\frac{3}{100}+\frac{4}{25}\)
\(=\frac{67}{100}+\frac{4}{25}\)
\(=\frac{67}{100}+\frac{16}{100}\)
\(=\frac{83}{100}=0,83\)
\(\frac{6}{11}x\frac{3}{7}+\frac{3}{7}x\frac{5}{11}\)
\(=\frac{18}{77}+\frac{15}{77}\)
\(=\frac{33}{77}=\frac{3}{7}\)
\(49x\left(311-4807:23\right)+98210\)
\(=49x\left(311-209\right)+98210\)
\(=49x102+98210\)
\(=4998+98210\)
\(=103208\)
a) \(\frac{7}{10}-\frac{3}{10}\times\frac{1}{10}+\frac{4}{25}\)
\(=\frac{2}{5}\times\frac{1}{10}+\frac{4}{25}\)
\(=\frac{1}{25}+\frac{4}{25}\)
\(=\frac{5}{25}=\frac{1}{5}\)
b)\(\frac{6}{11}\times\frac{3}{7}+\frac{3}{7}\times\frac{5}{11}\)
\(=\frac{3}{7}\times\left(\frac{6}{11}+\frac{5}{11}\right)\)
\(=\frac{3}{7}\times1\)
\(=\frac{3}{7}\)
c)\(49\times\left(311-4807:23\right)+98210\)
\(=49\times\left(311-209\right)+98210\)
\(=49\times102+98210\)
\(=4998+98210\)
\(=103208\)
a) X = 15
b) X = 4
c ) X= 23
d) X= 11
( Chỉ là ý kiến riêng thôi nhé, nhận gạch đá )
a) \(\frac{6+x}{33}=\frac{7}{11}\)
=> (6 + x). 11 = 33.7
=> 66 + 11x = 231
=> 11x = 231 - 66
=> 11x = 165
=> x = 165 : 11
=> x = 15
b) 15/26 + x/13 = 46/52
=> x/13 = 23/26 - 15/26
=> x/13 = 4/13
=> x = 4
c) 121/27 x 54/11 < x < 100/21 : 25/126
=> 22 < x < 24
=> x = 23 (vì x là số tự nhiên)
d) 1 < 11/x < 12
=> 11/x \(\in\){2; 3; 4 ; ...; 11}
=> x \(\in\) {11/2; 11/3; ...; 1}
Vì x là số tự nhiên => x = 1
\(\dfrac{32}{21}\times\dfrac{49}{45}:\dfrac{16}{22}\times\dfrac{15}{33}\)
\(=\dfrac{32}{21}\times\dfrac{49}{35}\times\dfrac{22}{16}\times\dfrac{15}{33}\)
\(=\dfrac{2\times16\times7\times7\times2\times11\times3\times5}{3\times7\times5\times7\times16\times3\times11}\)
\(=\dfrac{2\times2}{3}\)
\(=\dfrac{4}{3}\)
\(\frac{33}{49}\times\frac{25}{11}\times\frac{7}{15}\)
\(=\frac{33\times25\times7}{49\times11\times15}\)
\(=\frac{3\times5\times1}{7\times1\times3}\)
\(=\frac{5}{7}\)
\(\frac{33}{49}\cdot\frac{25}{11}\cdot\frac{7}{15}=\frac{3\cdot11\cdot5\cdot7\cdot5}{3\cdot11\cdot5\cdot7\cdot7}=\frac{5}{7}\)