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`@` `\text {Ans}`
`\downarrow`
`a,`
`(x-1954) \times 5=50`
`x-1954 = 50 \div 5`
`x-1954 = 10`
`x=10 + 1954`
`x= 1964`
`B.`
`48 - 40 \times x=8`
`40 \times x=48-8`
`40 \times x = 40`
` x=40 \div 40`
`x=1`
`C.`
`2+70 \div x = 3`
`70 \div x = 3-2`
`70 \div x = 1`
`x=70 \div 1`
`x=70`
`D. [3 \times (x+2) \div 7] \times 4=120`
`3 \times (x+2) \div 7 = 120 \div 4`
`3 \times (x+2) \div 7 =30`
`3 \times (x+2) = 30 \times 7`
`3 \times (x+2)=210`
`x+2=210 \div 3`
`x+2=70`
`x=70-2`
`x=68`
`E.`
`7,2 \div [ (0,6 \times x+8) \div 20 + 59] = 0,12?` Thiếu ngoặc bạn nhé._.
\(a,\left(x-1954\right)\times5=50\\ x-1954=50:5\\ x-1954=10\\ x=1954+10\\ x=1964\\b.48-40\times x=8\\40\times x=48-8\\40\times x=40\\ x=40:40\\ x=1 \\ c.2+70:X=3\\ 70:x=3-2\\ 70:x=1\\ x=70:1\\ x=70\\ d,\left[3\times\left(x+2\right):7\right]\times4=120\\ 3\times\left(x+2\right):7-120:4\\ 3\times\left(x+2\right):7=30\\ \left(x+2\right):7=30:3\\ \left(x+2\right):7=10\\ x+2=10\times7\\ x+2=70\\ x=70-2\\ x=68\)
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7,2 x 2,8 + 7,3 x 7,2 = 7,3 x (2,8 + 7,2)
= 7,3 x 10 = 73
54,57 x 83 - 54,57 x 23 = 54,57 x (83 - 23)
= 54,57 x 60 = 3274,2
1/2 x 45 + 0,5 x 37 + 5/10 x 18
= 0,5 x 45 + 0,5 x 37 + 0,5 x 18
= 0,5 x (45 + 37 + 18 )
= 0,5 x 100 = 50
0,125 x 4 x 784 x 8
= (0,125 x 8) x ( 4 x 784)
= 1 x 3136 = 3136
7,2 x 2,8 + 7,3 x 7,2
=7,2x(2,8+7,3)
=7,2x10,1
=72,72
54,57 x 83 - 54,57 x 23
=54,57 x (83-23)
=54,57 x 60
=3274,2
1/2 x 45 + 0,5 x 37 + 5/10 x 18
=1/2 x 45+1/2 x 37+1/2 x 18
=1/2 x (45+37+18)
=1/2 x 100
=50
0, 125 x 4 x 784 x 8
=(0,125 x 8) x (784 x 4)
=1 x 3136
=3136
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a,\(\Rightarrow x:3=1,56+7,2\)
\(\Rightarrow x:3=8,76\)
\(\Rightarrow x=8,76\cdot3\)
\(\Rightarrow x=26,28\)
b,\(\Rightarrow x:6=1,248:4\)
\(\Rightarrow x:6=0,312\)
\(\Rightarrow x=0,312\cdot6\)
\(\Rightarrow x=1,872\)
c,(x+x+x+x+...+x)+(2+5+8+....+29)=165
10 số hạng 10 số hạng
\(\Rightarrow\)10x+(29+2)*10:2=165
\(\Rightarrow\)10x+155=165
\(\Rightarrow10x=165-155\)
\(\Rightarrow10x=10\)
\(\Rightarrow x=10:10\)
\(\Rightarrow x=1\)
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anh dai dien dep day!!! Giai ne .
7,2:2x57,2+ 2,86x2x64 / 4+4+8+12+20+...+220
= 7,2:2x2x28,6 + 2,86x2x64 / 4+4+8+12+20+32+52+84+136+220
= 0,72x286 + 0,72x286 / 2x2+x12x2+x52x2+x220x2
= (0,72+1,28)x286 / 2x(2+12+52+220) = 2x286 / 2x286 = 1
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A. 7,2 x 2,8 + 7,3 x 7,2
= 7,2 x ( 2,8 + 7,3 )
= 7,2 x 10,1
= 72,72
B. 54,57 x 83 - 54,57 x 23
= 54,57 x ( 83 - 23 )
= 54,57 x 60
= 3274,2
C. 0,125 x 4 x 7 x 84 x 8
= ( 0,125 x 8) x ( 4 x 7 x 84)
= 1 x 2352
= 2352
D. 6,953 x 3,7 + 6,953 x 6,2 + 6,953 x 0,1
= 6,953 x ( 3,7 + 6,2 + 0,1)
= 6,953 x 10
= 69,53
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a) X + 20% x X = 7,2
100% X + 20% x X = 7,2
( 100% + 20% ) x X = 7,2
120% x X = 7,2
X = 7,2 : 120%
X = 6
b) X - 20% x X = 216
100% X - 20% x X = 216
( 100% - 20% ) x X = 216
80% x X = 216
X = 216 : 80%
X = 270
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x + 20% * x = 7.2
x +1/5 * x = 7.2
x * ( 1 + 1/5 ) = 7.2
x * 1.2 = 7.2
x = 7.2 : 1.2
x = 6
40% * x + x * 20% = 72
2/5 * x + x * 1/5 = 72
( 2/5 + 1/5 ) * x = 72
0.6 * x = 72
x = 72 : 0.6
x = 120
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\(X\times20o/o+X=7,2\)
\(\Leftrightarrow\)2x+0,2=7,2
\(\Leftrightarrow\)2x =7,2-0,2
\(\Leftrightarrow\)2x = 7
\(\Rightarrow\) x =7:2
\(\Rightarrow\)x =3,5
\(40o/o\times X+X\times20o/o=72\)
\(\Leftrightarrow0,4\times X+X\times0,2=72\)
\(\Leftrightarrow X\times\left(0,4+0,2\right)=72\)
\(\Leftrightarrow X\times0,6=72\)
\(\Rightarrow X=72:0,6\)
\(\Rightarrow X=120\)