tim x
x. 0 = 0
23( x - 4) =23
12x + 40 = 76
207 +( x + 35) = 312
(x - 6) . 25 = 0
12x + 13x = 25
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Lê Hoàng Khả Nhi
a, x.0 = 0
=> x = 0
b, 23( x -4) = 23
=> x -4 = 23/23
=> x -4 = 1
=> x = 1 + 4
=> x = 5
c, 12x + 40 = 76
=> 12x = 76 -40
=> 12x = 36
=> x = 36/12
=> x = 3
a) \(x.0=0\)
\(=>x\)có vô số nghiệm
b) \(23\left(x-4\right)=23\)
\(23x-92=23\)
\(23x=115\)
\(x=5\)
vậy \(x=5\)
c) \(12x+40=76\)
\(12x=36\)
\(x=3\)
vậy \(x=3\)
\(12\left(x+5\right)+2x=130\\\Leftrightarrow 12x+60+2x=130\\ \Leftrightarrow14x=70\\ \Leftrightarrow x=5\\ ----\\ 23\left(x-5\right)-12x=138\\ \Leftrightarrow23x-115-12x=138\\ \Leftrightarrow23x-12x=138+115\\ \Leftrightarrow11x=253\\ \Leftrightarrow x=\dfrac{253}{11}=23\\ ----\\ 360-12x+23\left(x-5\right)=278\\ \Leftrightarrow360-12x+23x-115=278\\ \Leftrightarrow-12x+23x=278+115-360\\ \Leftrightarrow11x=33\\ \Leftrightarrow x=\dfrac{33}{11}=3\)
\(6\left(x+3\right)+3\left(x-5\right)=278\\ \Leftrightarrow6x+18-3x-15=278\\ \Leftrightarrow6x-3x=278+15-18\\ \Leftrightarrow3x=275\\ \Leftrightarrow x=\dfrac{275}{3}\\ ---\\ \left(7-x\right)\left(3x-90\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}7-x=0\\3x-90=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=7\\x=30\end{matrix}\right.\)
a, ( x + 1 ) + ( x + 2 ) + ... + ( x + 199 ) = 0
x + 1 + x + 2 + ... + x + 199 = 0
( x + x + ... + x ) + ( 1 + 2 + ... + 199 ) = 0
199x + 19900 = 0
199x = 0 - 19900
199x = -19900
x = -19900 : 199
x = -100
Vậy ...
b, ( x - 30 ) + ( x - 29 ) + ( x - 28 ) = 11
x - 30 + x - 29 + x - 28 = 11
( x + x + x ) - ( 30 + 29 + 28 ) = 11
3x - 87 = 11
3x = 11 + 87
3x = 98
x = \(\frac{98}{3}\)
Vậy ...
Sửa đề: \(\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}=-5\)Ta có: \(\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}=-5\)
\(\Leftrightarrow\dfrac{74-x}{26}+1+\dfrac{75-x}{25}+1+\dfrac{76-x}{24}+1+\dfrac{77-x}{23}+1+\dfrac{78-x}{22}+1=0\)
\(\Leftrightarrow\dfrac{100-x}{26}+\dfrac{100-x}{25}+\dfrac{100-x}{24}+\dfrac{100-x}{23}+\dfrac{100-x}{22}=0\)
\(\Leftrightarrow\left(100-x\right)\left(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}\right)=0\)
mà \(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}>0\)
nên 100-x=0
hay x=100
Vậy: S={100}
Ta có : \(\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}=-5\)
\(\Leftrightarrow\dfrac{74-x}{26}+\dfrac{75-x}{25}+\dfrac{76-x}{24}+\dfrac{77-x}{23}+\dfrac{78-x}{22}+5=0\)
\(\Leftrightarrow\dfrac{74-x}{26}+1+\dfrac{75-x}{25}+1+\dfrac{76-x}{24}+1+\dfrac{77-x}{23}+1+\dfrac{78-x}{22}+1=0\)
\(\Leftrightarrow\dfrac{100-x}{26}+\dfrac{100-x}{25}+\dfrac{100-x}{24}+\dfrac{100-x}{23}+\dfrac{100-x}{22}=0\)
\(\Leftrightarrow\left(100-x\right)\left(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}\right)=0\)
Thấy : \(\dfrac{1}{26}+\dfrac{1}{25}+\dfrac{1}{24}+\dfrac{1}{23}+\dfrac{1}{22}\ne0\)
\(\Rightarrow100-x=0\)
\(\Leftrightarrow x=100\)
Vậy ...
a) 3636:(12x-91) =36
12x-91 = 3636:36
12x-91=101
12x=101+91
12x=192
x=192:12
x=16
b) (x : 23+45).67=8911
(x : 23+45)=8911:67
(x : 23+45)=133
x:23=133-45
x:23=88
x=88.23
x=2024
c) 420+65.4 =(x+175):5+30
420+260=(x+175):5+30
680=(x+175):5+30
(x+175):5=680-30
(x+175):5=650
(x+175)=650x5
(x+175)=3250
x=3250-175
x=3075
d) (32.15):2=(x+70):14-10
480:2=(x+70):14-10
240=(x+70):14-10
(x+70):14=240+10
(x+70):14=250
(x+70)=250.14
(x+70)=3500
x=3500-70
x=3430
e)x-4867=(175.2-50.70):25+23
x-4867=(350-3500):25+23
x-4867=-3150:25+23
x-4867=-126+23
x-4867=-103
x=-103+4867
x=4764
`x.0=0`
`=> x ∈N`
_____________________
`23.(x-4)=23`
`x-4=23:23`
`x-4=1`
`x=1+4`
`x=5`
_____________________
`12x+40=76`
`12x=76-40`
`12x=36`
`x=36:12`
`x=3`
______________________
`207+(x+35)=312`
`x+35=312-207`
`x+35=105`
`x=105-35`
`x=70`
___________________
`(x-6).25=0`
`x-6=0:25`
`x-6=0`
`x=0+6`
`x=6`
_______________
`12x+13x=25`
`(12+13)x=25`
`25x=25`
`x=25:25`
`x=1`
`x.0=0`
`0=0` (Luôn đúng)
`=>` Mọi giá trị của `x` đều t/m
___________________________________
`23(x-4)=23`
`x-4=23:23=1`
`x=1+4=5`
___________________________________
`12x+40=76`
`12x=76-40=36`
`x=36:12=3`
___________________________________
`207+(x+35)=312`
`x+35=312-207=105`
`x=105-35=70`
___________________________________
`(x-6).25=0`
`x-6=0:25=0`
`x=6`
___________________________________
`12x+13x=25`
`(12+13)x=25`
`25x=25`
`x=25:25=1`