x+x+x+x*8+7=71
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a,=(3+5+7+...+99) x (5-5)
=(3+5+7+...+99)x0
= 0
b, =(64+71-35)x8
=100x8
=800
K MK NHA PẠN
\(\frac{20}{7}.\frac{13}{8}+\frac{71}{8}.\frac{20}{8}-\frac{13}{8}.\frac{20}{7}\)
\(=\frac{20}{8}.\frac{13}{7}+\frac{71}{8}.\frac{20}{8}-\frac{20}{8}.\frac{13}{7}\)
\(=\frac{20}{8}.\left(\frac{13}{7}+\frac{71}{8}-\frac{13}{7}\right)\)
\(=\frac{20}{8}.\left(0+\frac{71}{8}\right)\)
\(=\frac{20}{8}.\frac{71}{8}\)
\(=\frac{355}{16}\)
Ủng hộ mk nha ^_-
\(\frac{20}{7}\cdot\frac{13}{8}+\frac{71}{8}\cdot\frac{20}{8}-\frac{13}{8}\cdot\frac{20}{7}=\frac{71}{8}\cdot\frac{5}{2}=\frac{355}{16}\)
1, <=>33+x=45
<=> x = 12
Vậy x=12
2, <=>x+73 =102
<=> x =29
3,x=2
4, -23+x=25<=>x=2
6, x-8=20<=>x=28
\(\frac{5+8+11+14+...+68+71}{2\times43+3\times43+43\times5+7}\).
Xét tử số: 5+ 8+ 11+ 14+...+ 68.
Có số các số hạng là:
( 68- 5): 3+ 1= 22
Tử số là:
( 68+ 5)x 22: 2= 803
Xét mẫu số: 2x 43+ 3x 43+ 43x 5+ 7=( 2+ 3+ 5)x 43+ 7= 10x 43+ 7= 430+ 7= 437.
=> \(\frac{5+8+11+14+...+68+71}{2\times43+3\times43+43\times5+7}\)= \(\frac{803}{437}\).
\(1,\Leftrightarrow7x=42\Leftrightarrow x=6\\ 2,\Leftrightarrow36-4x=4\Leftrightarrow4x=32\Leftrightarrow x=8\\ 3,\Leftrightarrow3x=35\Leftrightarrow x=\dfrac{35}{3}\\ 4,\Leftrightarrow x-12=144\Leftrightarrow x=156\\ 5,\Leftrightarrow x-14=16\Leftrightarrow x=30\\ 6,\Leftrightarrow3x-24=\dfrac{148}{73}\Leftrightarrow3x=\dfrac{1900}{73}\Leftrightarrow x=\dfrac{1900}{219}\\ 7,\Leftrightarrow33+x=45\Leftrightarrow x=12\\ 8,Sai.đề\\ 9,\Leftrightarrow\left(x+9\right):2=39\Leftrightarrow x+9=78\Leftrightarrow x=69\\ 11,\Leftrightarrow2\left(x+7\right)=38\Leftrightarrow x+7=19\Leftrightarrow x=12\\ 13,\Leftrightarrow2\left(x-51\right)=66\Leftrightarrow x-51=33\Leftrightarrow x=84\)
\(15,\Leftrightarrow x-19=9\Leftrightarrow x=28\\ 17,\Leftrightarrow\left(x-3\right):2=48\Leftrightarrow x-3=96\Leftrightarrow x=99\\ 19,\Leftrightarrow0x=46\Leftrightarrow x\in\varnothing\\ 8,Sai.đề\\ 14,\Leftrightarrow2x=209\Leftrightarrow x=\dfrac{209}{2}\\ 16,\Leftrightarrow2x+6=157\Leftrightarrow2x=151\Leftrightarrow x=\dfrac{151}{2}\\ 18,\Leftrightarrow5\left(x+4\right)=100\Leftrightarrow x+4=20\Leftrightarrow x=16\\ 20,\Leftrightarrow\left(3x-5\right)^3=27=3^3\Leftrightarrow3x-5=3\Leftrightarrow x=\dfrac{8}{3}\)
a) \(\Leftrightarrow-x+38=26\)
\(\Leftrightarrow x=12\)
b)\(\Leftrightarrow x+47=76\)
\(\Leftrightarrow x=29\)
c)\(\Leftrightarrow-x+36=6\)
\(\Leftrightarrow x=30\)
d)\(\Leftrightarrow x+16=20\)
\(\Leftrightarrow x=4\)
e)\(x-18=13\)
\(\Leftrightarrow x=31\)
f)\(-x+194=120\)
\(\Leftrightarrow x=74\)
g)\(\Leftrightarrow x-8=20\)
\(\Leftrightarrow x=28\)
h)\(\Leftrightarrow4x+84=400\)
\(\Leftrightarrow x=79\)
a) 71-(33+x)=26
33+x=71-26
33+x=45
x=45-33
x=12
Vậy x=12
b) ( x+73)-26=76
x+73=76+26
x+73=102
x=102-73
x=29
Vậy x=29
c)45-(x+9)=6
x+9=45-6
x+9=39
x=39-9
x=30
Vậy x=30
d) 89-(73-x)=20
73-x=89-20
73-x=69
x=73-69
x=4
Vậy x=4
e) ( x+7)-25=13
x+7=13+25
x+7=38
x=38-7
x=31
Vậy x=31
f)198-(x+4)=120
x+4=198-120
x+4=78
x=78-4
x=74
Vậy x=74
g)140:(x-8)=7
x-8=140:7
x-8=20
x=20+8
x=28
Vậy x=28
h) 4(x+41)=400
x+41=400:4
x+41=100
x=100-41
x=59
Vậy x=59
x+x+x+x*8+7= 71
4x *8+7= 71
4x *8 = 71-7
4x *8 = 64
4x = 64 : 8
4x = 8
x = 8 : 4
x = 2
Vậy x = 2.
tk mk đi mà !!!
x + x + x + x * 8 + 7 = 71
4x * 8 + 7 = 71
4x * 8 = 71 - 7
4x * 8 = 64
4x = 64 : 8
4x = 8
x = 8 : 4
x = 2