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\(\text{(x+1)+(x+2)+(x+3)+(x+4)+(x+5)+(x+6)+(x+7)+(x+8)+(x+9)=54}\)
\(\text{x+1+x+2+x+3+x+4+x+5+x+6+x+7+x+8+x+9=54}\)
\(9x+\left(1+2+3+4+5+6+7+8+9\right)=54\)
\(9x-45=54\)
\(9x=99\)
\(x=11\)
\(\text{(x+1)+(x+2)+(x+3)+(x+4)+(x+5)+(x+6)+(x+7)+(x+8)+(x+9)=54}\)
\(\text{x+1+x+2+x+3+x+4+x+5+x+6+x+7+x+8+x+9=54}\)
\(\text{9x + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 54 }\)
\(\text{9x − 45 = 54 }\)
\(\text{9x = 99 }\)
\(\text{x = 11}\)
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a) (x + 1) + (x + 2) + (x + 3) + ... + (x + 9) = 54
(x + x + x + ... + x) + (1 + 2 + 3 + ... + 9) = 54
9x + 45 = 54
9x = 54 - 45
9x = 9
x = 1
b) (x + 1) + (x + 2) + (x + 3) + ... + (x + 10) = 2010
(x + x + x + ... + x) + (1 + 2 + 3 + ... + 10) = 2010
10x + 55 = 2010
10x = 2010 - 55
10x = 1955
x = 391/2.
1)\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+....+\left(x+9\right)=54\)
\(\Rightarrow x+1+x+2+x+3+.....+x+9=54\)
\(\Rightarrow\left(x+x+x+....+x\right)+\left(1+2+3+....+9\right)=54\)
\(\Rightarrow9x+45=54\)\(\Rightarrow9x=9\Rightarrow x=1\)
2)\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+....+\left(x+10\right)=2010\)
\(\Rightarrow x+1+x+2+x+3+.....+x+10=2010\)
\(\Rightarrow\left(x+x+x+....+x\right)+\left(1+2+3+....+10\right)=2010\)
\(\Rightarrow10x+55=2010\Rightarrow10x=1995\Rightarrow x=195,5\)
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4/5.(x - 1/2) + (x + 7/8) = 54/4
4/5.(x - 1/2) + x + 7/8 = 27/2
4/5.(x - 1/2) + 5x + 35/8 = 135/2
4x - 2 + 5x + 35/8 = 135/2
9x + 19/8 = 135/2
9x = 135/2 - 19/8
9x = 521/8
x = 521/8.9
x = 521/72
"." là nhân
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a/ = 113 x ( 54 + 45 + 1 ) = 113 x 100 = 11300
b/ = 47 x ( 54 - 53 ) - 20 - 27 = 47 - 20 - 27 = 0
c/ = 145 x ( 99 + 1 ) - 143 x ( 101 - 1 ) = 145 x 100 - 143 x 100 = 100 x ( 145 - 143 ) = 100 x 2 = 200
d/ = 1002 x 9 - 2 x 9 = 9 x ( 1002 - 2 ) = 9 x 1000 = 9000
e/ = 24 x 427 + 24 x 573 = 24 x ( 427 + 573 ) = 24 x 1000 = 24000
f/ Sửa đề bài là :
2008 x 867 + 2008 x 133 = 2008 x ( 867 + 133 ) = 2008 x 1000 = 2008000
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Bài 1:
a) 43+45+47+...+565 [có (565-43)/2+1= 262 số hạng)
= [(565+43)*262]/2
= 79648
b) 21+24+27+...+318 [có (318-21)/3+1= 100 số hạng]
= [(318+21)*100]/2
= 16950
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a ) \(=\frac{35\cdot42}{5\cdot2}=\frac{7\cdot5\cdot2\cdot21}{5\cdot2}\)
\(=\frac{7\cdot21}{1}=147\)
b) \(=\frac{54\cdot35}{7\cdot9}\)
\(=\frac{6\cdot9\cdot7\cdot5}{7\cdot9}\)
\(=\frac{6\cdot5}{1}=30\)
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a) 3 x X x 2/3 = 4/5
3.x=6/5
x=2/5
b) 3,94 x 18,24 + 18,24 x 3,72 + 18,24 x 2,34
=18,24(3,94+3,72+2,34)
=18,24.10
=182,4
d) 8/19 x 2/7 + 8/19 x 1/7 + 8/19 x 4/7
=8/19(2/7+1/7+4/7)
=8/19.1
=8/19
(x +1) + (x+2) +...+(x+8) + (x+9) = 54
x +1 + x+2 +...+x+8 + x+9 = 54
9x + (1+9) + (2+8) + (3+7) + (4+6) + 5 = 54
9x + 45 = 54
9x = 9
x = 1
x = 1
bài này tính lâu quá !