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8 ⋮ \(x\); 12 ⋮ \(x\); 24 ⋮ \(x\) ⇒ 8; 12; 24 ⋮ \(x\) ⇒ \(x\) \(\in\) ƯC(8;12;24)
8 = 23; 12 = 22.3; 24 = 22.3
ƯCLN(8; 12; 24) = 22 = 4
\(x\) \(\in\) {-4; -2; -1; 1; 2; 4}
a,91-5(5+x)=61
=>25+5x=91-61=30
=>5x=30-25=5
=>x=1
b,\([\left(x+34\right)-50]\)x2=56
=>(x+34)-50=56:2=28
=>x+34=28+50=78
=>x=78-34=44.
c,1045-\([2015-\left(3x-24\right)]\)=5
=>2015-(3x-24)=1045-5=1040
=>3x-24=2015-1040=975
=>3x=975+24=999
=>x=999:3=333
d,\([195-\left(3x-27\right)]\)x39=4212
=>195-(3x-27)=4212:39=108
=>3x-27=195-108=87
=>3x=87+27=117
=>x=39
e,30-3(x-2)=18
=>30-3x+6=18
=>30-3x=18-6=12
=>3x=30-12=18
=>x=18:3=6
a) \(...\Rightarrow5\left(5+x\right)=91-61=30\)
\(\Rightarrow\left(5+x\right)=30:5=6\Rightarrow x=6-5=1\)
b) \(...\Rightarrow\left(x+34\right)-50=56:2=28\)
\(\Rightarrow\left(x+34\right)=28+50=78\Rightarrow x=78-34=44\)
c) \(...\Rightarrow2015-\left(3x-24\right)=1045-5=1040\)
\(\Rightarrow\left(3x-24\right)=2015-1040=975\)
\(\Rightarrow3x=975+24=999\Rightarrow x=999:3=333\)
d) \(...\Rightarrow195-\left(3x-27\right)=4212:39=108\)
\(\Rightarrow\left(3x-27\right)=195-108=87\)
\(\Rightarrow3x=87+27=114\Rightarrow x=114:3=38\)
e) \(...\Rightarrow3\left(x-2\right)=30-18=12\Rightarrow x-2=12:3=4\)
\(\Rightarrow x=4+2=6\)
a) 320 x 63 - 16 x 20 + 32 x 370
= 320 x 63 - 320 x + 320 x 37
= 320 x ( 63 - 1 + 37 )
= 320 x 99
= 320 x ( 100 - 1 )
= 320 x 100 - 320
= 32000 - 320 = 31 680
b) 35 x 61 + 215 x 5 + 35 x 39 + 57 x 25
= 5 x 427 + 5 x 215 + 5 x 273 + 5 x 285
= 5 x ( 427 + 215 + 273 + 285 )
= 5 x 1200 = 6000
c) 34 x 24 - 94 x 6 + 83 x 48 - 47 x 88
= 204 x 4 - 4 x 141 + 996 x 4 - 1034 x 4
= 4 x ( 204 - 141 + 996 - 1034 )
= 4 x 25 = 100
-5 - (24 - x ) = 12 + (42-65)
\(\Leftrightarrow\) -5-24-x = 12+42-65
\(\Leftrightarrow\) x - 29 = -11
\(\Leftrightarrow\) x = -11+29
\(\Leftrightarrow\) x = 18
a) `123 - 27 + 27 + 13 - 123`
`= (123 - 123) + (27 - 27) + 13`
`= 0 + 0 + 13`
`= 13`
`---`
b) `175 + 25 + 13 + 15 - 175 - 25`
`= (175-175)+(25-25)+25+13`
`=0+0+25+13`
`=28`
`---`
c) \(53\times39+47\times39+53\times21+47\times21\)
\(=\text{[}\left(53+47\right)\times39]+\left[\left(53+47\right)\times21\right]\)
\(=\left(100\times39\right)+\left(100\times21\right)\)
\(=3900+2100\)
`=6000`
`---`
d) \(49\times35+49\times16-49\times61\)
`=` \(49\times\left(35+16-61\right)\)
`=` \(49\times\left(-10\right)\)
`=-490`
\(a,91-5.\left(5+x\right)=61\\ \Rightarrow=5.\left(5+x\right)=30\\ \Rightarrow5+x=6\\ \Rightarrow x=1.\\ b,\left[195-\left(3x-27\right)\right].39=4212\\ \Rightarrow195-\left(3x-27\right)=108\\ \Rightarrow3x-27=87\\ \Rightarrow3x=114\\ \Rightarrow x=38.\)
\(91-5.\left(5+x\right)=61\)
\(\Rightarrow5.\left(5+x\right)=91-61\)
\(\Rightarrow5.\left(5+x\right)=30\)
\(\Rightarrow5+x=\dfrac{30}{5}=6\)
\(\Rightarrow x=6-5=1\)
\(\left[195-\left(3x-27\right)\right].39=4212\)
\(\Rightarrow195-3x+27=\dfrac{4212}{39}=108\)
\(\Rightarrow222-3x=108\)
\(\Rightarrow3x=222-108=114\)
\(\Rightarrow x=\dfrac{114}{3}=38\)
a: \(\Leftrightarrow x=\dfrac{16\cdot6}{4}=24\)
b: \(\Leftrightarrow x=\dfrac{-5\cdot42}{14}=-15\)
c: \(\Leftrightarrow\dfrac{x}{11}=\dfrac{-3}{11}\)
hay x=-3
42 . x = 39 . 42 - 37. 42
=> 42x=42.(39-37)
=> 42x=42.2
=> x=2
C = 39.42 + 24.61 - 39.18
= 39.(42 - 18) + 24.61
= 39.24 + 24.61
= 24.(39 + 61)
= 24.100
= 2400