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a,11-(15+21)=x-(25-9)
11-15-21=x-25+9
-x=-25+9-11+15+21
-x=9
x=-9
b,9-25=(7-x)-(25+7)
-16=7-x-32
x=7-32+16
x=-9
![](https://rs.olm.vn/images/avt/0.png?1311)
11 - 36 = x - 16
-25 = x - 16
x = 16 + (-25)
x = -9
2 - x = 17 + 5
2 - x = 22
x = 2 - 22
x= 20
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Ta có: \(x-12=\left(-9\right)-15\)
\(\Rightarrow x-12=-24\)
\(\Rightarrow x=-12\)
b) \(2-x=17-\left(-5\right)\)
\(\Rightarrow2-x=22\)
\(\Rightarrow x=2-22\)
\(\Rightarrow x=-20\)
c) \(11-\left(15+11\right)=x-\left(25-9\right)\)
\(\Rightarrow-15=x-16\)
\(\Rightarrow x=1\)
d) \(x-\left(17-x\right)=x-7\)
\(\Rightarrow x-17+x=x-7\)
\(\Rightarrow x+x-x=-7+17\)
\(\Rightarrow x=10\)
e) \(9-25=\left(7-x\right)-\left(25+7\right)\)
\(\Rightarrow9-25=7-x-25-7\)
\(\Rightarrow-16=-25-x\)
\(\Rightarrow x=-9\)
g) \(x-13=21-x\)
\(\Rightarrow x+x=21+13\)
\(\Rightarrow2x=34\)
\(\Rightarrow x=17\)
a, x - 12 = ( -9 ) - 15
x - 12 = -24
x = -24 + 12
x = -12
b, 2 - x = 17 - ( -5 )
2 - x = 22
x = 2 - 22
x = -20
c, 11 - ( 15 + 11 ) = x - ( 25 - 9 )
11 - 26 = x - 16
-15 = x - 16
x = -15 + 16
x = 1
d, x - ( 17 - x ) = x - 7
x - 17 + x = x - 7
x + x - 17 = x - 7
x + x - x = -7 + 17
x = 10
e.9 - 25 = ( 7- x ) - ( 25 + 7 )
-16 = ( 7 - x ) -32
7 - x = -32 + 16
7 - x = 16
x = 7 - 16
x= -9
g, x - 13 = 21 - x
x + x = 21 + 13
2x = 44
x = 44 : 2
x=22
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 15 - 3.( x - 2 ) = 21
=> 15 - 3x - 3.2 = 21
=> 15 - 3x - 6 = 21
=> -3x = 21 - 15 + 6
=> -3x = 0
=> x = 0
b, 9 - 25 = ( -7 - x ) - ( 25 - 7)
=> -16 = -7 - x - 25 + 7
=> -16 + 7 + 25 - 7 = x
=> 9 = x
c, 11 + ( 15 - 11 ) = x - ( 25 - 9 )
=> 11 + 15 - 11 = x - 25 + 9
=> 15 = x - 16
=> x = 15 + 16
=> x = 31
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{25^5+25^7+25^9}{5^{11}+5^{13}+5^{15}+5^{17}+5^{19}+5^{21}}\)
\(=\dfrac{5^{10}+5^{14}+5^{18}}{5^{11}+5^{13}+5^{17}+5^{19}+5^{21}}\)
\(=\dfrac{5^{10}\left(1+5^4+5^8\right)}{5^{11}\left(1+5^2+5^4+5^6+5^8+5^{10}\right)}\)
\(=\dfrac{1+5^4+5^8}{5+5^3+5^5+5^7+5^9+5^{11}}\)
\(=\dfrac{1+5^4+5^8}{\left(5+5^5+5^9\right)+\left(5^3+5^7+5^{11}\right)}\)
\(=\dfrac{1+5^4+5^8}{\left(1+5^4+5^8\right)\left(5+5^3\right)}\)
\(=\dfrac{1}{5+5^3}\)
\(=\dfrac{1}{130}\)
\(\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 35
b) -53
c) 40 – - 7 2 = 40 – 49 = -9
d)| -15 + 21| - | 4 – 11 | = | 6 | - | -7 | = 6 – 7 = -1
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(11-\left(15-21\right)=x-\left(25-9\right)\)
\(\Leftrightarrow11-15+21+25-9=x\)
\(\Leftrightarrow x=33\)
b) \(2-x=17-\left(-5\right)\)
\(\Leftrightarrow2-x=22\)
\(\Leftrightarrow x=-20\)
c) \(x-12=\left(-9\right)-15\)
\(\Leftrightarrow x-12=-24\)
\(\Leftrightarrow x=-12\)
d) \(9-25=\left(7-x\right)-\left(25+7\right)\)
\(\Leftrightarrow-16=7-x-25-7\)
\(\Leftrightarrow x=-9\)
a) 11-(15+21)=x-(25-9)
11-36=x-25+9
-25=x-(25+9)
-25=x-34
x=-25+34
x=9
Vậy x=9
b) 2-x=17-(-5)
2-x=22
x=2-22
x=-20
Vậy x=-20
c) x-12=(-9)-15
x-12=-24
x=-24+12
x=-12
Vậy x=-12
d) 9-25=(7-x)-(25+7)
16=7-x-32
48=7-x
x=-41
Vậy x=-41
11 - (15 + 21) = x - (25 - 9)
=> 11 - 36 = x - 16
=> x - 16 = -25
=> x = -25 + 16
=> x = -9
vậy_
Trả lời
11-(15+21)=x-(25-9)
11-36 =x-16
25 =x-16
x-16 =25
x =25+16
x =41.
Học tốt nha !