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Câu 1
=> ( 2x-15)^3 - (2x -15)^5=0
(2x-15)^3 * ( -(2x-15)^2+1) =0
xét 2 TH : + (2x-15)^3=0
+ 1-(2x-15)^2 =0
=> ĐPCM
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a) 2\(^3\).15 -[115-(12-5)\(^2\)]
= 8.15-[115-(7)\(^2\)]
= 120-[115-49]
= 120-66
= 54
c)4.5\(^2\)- 81:3\(^2\)+3\(^2\).22-3\(^3\).19
=4.25-81:9+9.22-27.19
=100-9+198-513
=91+198-513
=289-513
=(-224)
Câu b sai đề nhé bn
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a) 23.15 - [115 - (12-5)2]
= 8.15 - [115 - 72]
= 120 - [115 - 49]
= 120 - 66
= 54
b) 30 : {175 : [355 - (135+37.5)]}
= 30 : {175 : [355 - (135 + 185)]}
= 30 : {175 : [355 - 320]}
= 30 : {175 : 35}
= 30 : 5
= 6
c) 12 : {390 : [500 - (125+35.7)]}
= 12 : {390 : [500 - (125+245)]}
= 12 : {390 : [500 - 370]}
= 12 : {390 : 130}
= 12 : 3
= 4
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a: \(\Leftrightarrow-\dfrac{450}{-115-15\left(2x-1\right)^2}=8\cdot5-37=3\)
\(\Leftrightarrow\dfrac{450}{115+15\left(2x-1\right)^2}=3\)
\(\Leftrightarrow115+15\left(2x-1\right)^2=150\)
=>15(2x-1)2=35
=>(2x-1)2=7/3
hay \(x\in\left\{\dfrac{3+\sqrt{21}}{6};\dfrac{3-\sqrt{21}}{6}\right\}\)
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\(2^5.3^2+2^5.11-2^6.5-5\)
\(=2^5.9+2^5.11-2^5.2^1.5-5\)
\(=2^5.\left(9+11-2.5\right)-5\)
\(=32.\left(9+11-10\right)-5\)
\(=32.10-5\)
\(=320-5\)
\(=315\)
\(-2017-\left[\left(15-2017\right)+\left(-115\right)\right]\)
\(=-2017-\left[\left(-2002\right)+\left(-115\right)\right]\)
\(=-2017-\left(-2117\right)\)
\(=-2017+2117\)
\(=100\)
Vì 24 chia hết cho x, 120 chia hết cho x và 10<x<20 nên x ƯC(24,120)
Ta có : 24 =12.2 ; 120= 10.12
ƯCLN(24,120) = 12
Mà Ư(12) = { 1,2,3,4,6,12}
=>ƯC(24,120) = { 1,2,3,4,6,12}
Vì 10<x<20
=> x = 12
Vậy x = 12
3.|x-1| = 28:23 + 20170
3.|x-1| = 25+ 1
3.|x-1| = 32 + 1
3.|x-1| = 33
|x-1| = 33 : 3
|x-1| =11
=> x -1 =11
x = 11+1
x = 22