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![](https://rs.olm.vn/images/avt/0.png?1311)
binh rồi căn thì cứ chuyển bỏ dấu âm đi nó tương tự dấu giá trị tuyệt đối thôi
![](https://rs.olm.vn/images/avt/0.png?1311)
\(c,-5\left(2-x\right)+4\left(x-3\right)=10x-15\)
\(-10+5x+4x-12=10x-15\)
\(5x+4x-10x-10-12=-15\)
\(-x-10=-3\)
\(-x=7\)
\(x=-7\)
Vậy \(x=-7.\)
Những câu khác bạn nên tự làm...
a) −7. (5 - x) − 2. (x − 10) = 15
-35 + 7x - 2x + 20 = 15
7x - 2x = 35 - 20 + 15
5x = 30
x = 30 : 5
x = 6
Vậy x = 6
b) 4. (2 − x) + 3(x − 5) = 14
8 - 4x + 3x - 15 = 14
8 - 15 - 14 = 4x - 3x
-21 = x
Vậy x = -21
c) −5. (2 − x) + 4. (x − 3) = 10x −15
-10 + 5x + 4x - 12 = 10x - 15
-10 - 12 + 15 = 10x - 5x - 4x
-7 = x
Vậy x = -7
d) −7. (3x − 5) + 2. (7x − 14) = 28
-21x + 35 + 14x - 28 = 28
35 - 28 - 28 = 21x - 14x
-21 = 7x
x = (-21) : 7
x = -3
Vậy x = -3
e) 5. (4 − x) − 7(−x + 2) = 4 − 9 + 3
20 - 5x + 7x - 14 = -2
-5x + 7x = -2 - 20 + 14
2x = -8
x = (-8) : 2
x = -4
Vậy x = -4
f) 5. (x − 7) + 10. (3 − x) = 20
5x - 35 + 30 - 10x = 20
-35 + 30 - 20 = -5x + 10x
-25 = 5x
x = (-25) : 5
x = -5
Vậy x = -5
g) −4. (x + 1) + 8. (x − 3) = 24
-4x - 4 + 8x - 24 = 24
-4x + 8x = 24 + 4 + 24
4x = 52
x = 52 : 4
x = 13
Vậy x = 13
h) 4. (x − 1) − 3. (x − 2) = −|−5|
4x - 4 - 3x + 6 = -5
4x - 3x = -5 + 4 - 6
x = -7
Vậy x = -7
![](https://rs.olm.vn/images/avt/0.png?1311)
ta có : \(5^x.5^{\left(x+1\right)}.5^{\left(x+2\right)}\le\dfrac{100...0}{2^{18}}\) \(\Leftrightarrow5^{3x+3}\le\dfrac{10^{18}}{2^{18}}=5^{18}\)
\(\)\(\Leftrightarrow3x+3\le18\Leftrightarrow x\le5\) vậy \(x\le5\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =>1/3x+2/5x-2/5=0
=>11/15x-2/5=0
=>11/15x=2/5
=>x=2/5:11/15=2/5*15/11=30/55=6/11
b: =>-5x-1-1/2x+1/3=x
=>-11/2x-2/3-x=0
=>-13/2x=2/3
=>x=-2/3:13/2=-2/3*2/13=-4/39
c: (x+1/2)(2/3-2x)=0
=>x+1/2=0 hoặc 2/3-2x=0
=>x=1/3 hoặc x=-1/2
d: 9(3x+1)^2=16
=>(3x+1)^2=16/9
=>3x+1=4/3 hoặc 3x+1=-4/3
=>3x=1/3 hoặc 3x=-7/3
=>x=1/9 hoặc x=-7/9
![](https://rs.olm.vn/images/avt/0.png?1311)
b/100x+(1+2+3+...+100)=205550
100x+5050=205550
100x=205550-5050
100x=200500
x=200500/100
x=2005
d/(3x-24).75=2.76.1/20090
(3x-24).75=2.76.1
(3x-24)=2.76:75
(3x-24)=2.7
3x-16=14
3x=14+16
3x=30
x=30/10=3
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =>1/2x=7/2-2/3=21/6-4/6=17/6
=>x=17/3
b: =>2/3:x=-7-1/3=-22/3
=>x=2/3:(-22/3)=-1/11
c: =>1/3x+2/5x-2/5=0
=>11/15x=2/5
hay x=6/11
d: =>2x-3=0 hoặc 6-2x=0
=>x=3/2 hoặc x=3
![](https://rs.olm.vn/images/avt/0.png?1311)
a/ \(3+2^{x-1}=24-\left[4^2-\left(2^2-1\right)\right]\\3+2^{x+1}=24-\left[16-\left(4-1\right)\right]\)
\(3+2^{x+1}=24-\left(16-3\right)\\ 3+2^{x-1}=24-13\\ 3+2^{x-1}=11\\ 2^{x+1}=11-3\\ 2^{x-1}=8\)
\(2^{x-1}=2^3\\ \Rightarrow x-1=3\\x=3+1\\ x=4\)
\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+100\right)=205550\)
\(\left(x.100\right)+\left(1+2+3+....+100\right)=205550\)
Ta tính tổng \(1+2+3+...+100\\ \) trước
Số các số hạng: \(\left[\left(100-1\right):1+1\right]=100\)
Tổng :\(\left[\left(100+1\right).100:2\right]=5050\)
Thay số vào ta có được:
\(\left(x.100\right)+5050=205550\\ \\ x.100=205550-5050\\ \\x.100=20500\\ \\x=20500:100\\ \\\Rightarrow x=2005\)