1. Tìm x, biết:
a. x + 15 = 27
b. 2x + 3 = 15
c. 5 + 3x = 17
d. 3x + 17 = 23
2. Tính tổng:
20 + 30 + ... + 200.
bài 19: tìm x
c) ( 34 - 2x ) . ( 2x - 6 ) = 0
d) ( 2019 - x ) . ( 3x - 12 ) 0
e) 57 . ( 9x - 27 ) = 0
f) 25 + ( 15 - x ) = 30
g) 43 - ( 24 - x ) = 20
h) 2 . ( x - 5 ) - 17 = 25
i) 3 . ( x + 7 ) - 15 = 27
j) 15 + 4 . ( x - 2 ) = 95
k) 20 - ( x + 14 ) = 5
l) 14 + 3 . ( 5 - x ) = 27
nhanh nha, mik tick cho, ccau trình bày dễ hiểu, ko cần ''hoặc''
`@` `\text {Ans}`
`\downarrow`
`c)`
`( 34 - 2x ) . ( 2x - 6 ) = 0`
`=>`\(\left[{}\begin{matrix}34-2x=0\\2x-6=0\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}2x=34\\2x=6\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=34\div2\\x=6\div2\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=17\\x=3\end{matrix}\right.\)
Vậy, `x \in {17; 3}`
`d)`
`( 2019 - x ) . ( 3x - 12 ) =0` `?`
`=>`\(\left[{}\begin{matrix}2019-x=0\\3x-12=0\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=2019-0\\3x=12\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=2019\\x=12\div3\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=2019\\x=4\end{matrix}\right.\)
Vậy, `x \in {2019; 4}`
`e) `
`57 . ( 9x - 27 ) = 0`
`=>`\(9x-27=0\div57\)
`=> 9x - 27 = 0`
`=> 9x = 27`
`=> x = 27 \div 9`
`=> x = 3`
Vậy, `x = 3`
`f)`
`25 + ( 15 - x ) = 30`
`=> 15 - x = 30 - 25`
`=> 15 - x = 5`
`=> x = 15 -5 `
`=> x = 10`
Vậy, `x = 10`
`g) `
`43 - ( 24 - x ) = 20`
`=> 24 - x = 43 - 20`
`=> 24 - x = 23`
`=> x = 24 - 23`
`=> x = 1`
Vậy, `x = 1`
`h) `
`2 . ( x - 5 ) - 17 = 25`
`=> 2 ( x - 5) = 25+17`
`=> 2 ( x - 5) = 42`
`=> x - 5 = 42 \div 2`
`=> x - 5 = 21`
`=> x = 21 + 5`
`=> x = 26`
Vậy, `x = 26`
`i)`
`3 . ( x + 7 ) - 15 = 27`
`=> 3(x + 7) = 27 + 15`
`=> 3(x + 7) = 42`
`=> x +7 = 42 \div 3`
`=> x + 7 = 14`
`=> x = 14 - 7`
`=> x = 7`
Vậy, `x = 7`
`j)`
`15 + 4 . ( x - 2 ) = 95`
`=> 4(x - 2) = 95 - 15`
`=> 4(x - 2) = 80`
`=> x - 2 = 80 \div 4`
`=> x - 2 = 20`
`=> x = 20 + 2`
`=> x = 22`
Vậy, `x = 22`
`k)`
`20 - ( x + 14 ) = 5`
`=> x + 14 = 20 - 5`
`=> x + 14 = 15`
`=> x = 15 - 14`
`=> x = 1`
Vậy, `x = 1`
`l) `
`14 + 3 . ( 5 - x ) = 27`
`=> 3(5 - x) = 27 - 14`
`=> 3(5 - x) = 13`
`=> 5 - x = 13 \div 3`
`=> 5 - x = 13/3`
`=> x = 5- 13/3`
`=> x = 2/3`
Vậy, `x = 2/3.`
`@` `\text {Kaizuu lv uuu}`
bài 19: tìm x
a) 5 . ( x - 7 ) = 0
b) 25 ( x - 4 ) = 0
c) ( 34 - 2x ) . ( 2x - 6 ) = 0
d) ( 2019 - x ) . ( 3x - 12 ) 0
e) 57 . ( 9x - 27 ) = 0
f) 25 + ( 15 - x ) = 30
g) 43 - ( 24 - x ) = 20
h) 2 . ( x - 5 ) - 17 = 25
i) 3 . ( x + 7 ) - 15 = 27
j) 15 + 4 . ( x - 2 ) = 95
k) 20 - ( x + 14 ) = 5
l) 14 + 3 . ( 5 - x ) = 27
a) \(5\left(x-7\right)=0\)
\(\Rightarrow x-7=0\)
\(\Rightarrow x=7\)
b) \(25\left(x-4\right)=0\)
\(\Rightarrow x-4=0\)
\(\Rightarrow x=4\)
c) \(\left(34-2x\right)\left(2x-6\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}34-2x=0\\2x-6=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}2x=34\\2x=6\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=17\\x=3\end{matrix}\right.\)
d) \(\left(2019-x\right)\left(3x-12\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2019-x=0\\3x-12=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2019\\3x=12\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2019\\x=\dfrac{12}{3}=4\end{matrix}\right.\)
e) \(57\left(9x-27\right)=0\)
\(\Rightarrow9x-27=0\)
\(\Rightarrow9\left(x-3\right)=0\)
\(\Rightarrow x-3=0\)
\(\Rightarrow x=3\)
a) 5.(x-7)=0⇔x-7=0⇔x=7
b) 25(x-4)=0⇔x-4=0⇔x=4
c) (34-2x).(2x-6)=0
⇔ 34-2x=0 hoặc 2x-6=0
⇔2x=34 hoặc 2x=6
⇔ x=17 hoặc x=3
d) (2019-x).(3x-12)=0
⇔ 2019-x=0 hoặc 3x-12=0
⇔ x=2019 hoặc x=4
e) 57.(9x-27)=0
⇔ 9x-27=0
⇔ x=3
f) 25+(15-x)=30
⇔ 15-x=5
⇔ x=10
g) 43-(24-x)=20
⇔ 24-x=23
⇔ x=1
h) 2.(x-5)-17=25
⇔ 2(x-5)=42
⇔x-5=21
⇔ x=26
i) 3(x+7)-15=27
⇔ 3(x+7)=42
⇔ x+7=14
⇔ x=7
j) 15+4(x-2)=95
⇔ 4(x-2)=80
⇔ x-2=20
⇔ x=22
k) 20-(x+14)=5
⇔ x+14=15
⇔ x=1
l) 14+3(5-x)=27
⇔ 3(5-x)=13
⇔ 5-x=13/3
⇔ x=5-13/3
⇔ x=2/3
Bài 1 Tính:
a) 75-5.(15-10)-(-60)
b) 136-(-7)+6-23-36
c) (-15-17).(-15+7)
d) (-9-18):(-9)
Bìa 2 Tìm x:
a) 2x-17=(-3x-18)
b) (13-IxI) +15=20
c) Ix+5I-(x+5)=0
a, 75 - 5 . ( 15 - 10 ) - ( -60 ) = 75 - 5 . 5 + 60 = 135 - 25 = 110
b, 136 - ( -7 ) + 6 - 23 - 36 = 136 + 7 + 6 - 23 - 36 = ( 136 - 36 ) + ( 7 + 6 - 23 ) = 100 - 10 = 90
c, ( -15 - 17 ) . ( -15 + 7 ) = -32 . ( -8 ) = 256
d, ( -9 - 18 ) : ( -9 ) = -27 : ( -9 ) = 3
Bài 2:
a, 2x - 17 = ( -3x - 18 )
<=> 2x + 3x = 17 - 18
<=> 5x = -1
<=> x = -1/5
b, ( 13 - IxI ) + 15 = 20
<=> 13 - |x| = 5
<=> |x| = 8
<=> x = 8 hoặc x = -8
c, Ix + 5I - ( x + 5 ) = 0
<=> |x + 5| = x + 5
Đk: x + 5 ≥ 0 => x ≥ -5
\(\Leftrightarrow\orbr{\begin{cases}x+5=x+5\\x+5=-x-5\end{cases}\Leftrightarrow}\orbr{\begin{cases}0x=0\\2x=-10\end{cases}\Leftrightarrow}\orbr{\begin{cases}x\ge-5\\x=-5\end{cases}}\)
Vậy x ≥ -5
Câu 1:
a) -2x-(x-17)=34-(-x+25)
b) 17x-(-16x-27)=2x+43
c) -2x-3(x-17)=34-2(-x+25)
d) 17x+3(-16x-37)=2x+43-4x
e) 3x-32>-5x+1
f)15+4x<2x-145
g)-3(2x+5)-16<-4(3-2x)
h) -2x+15<3x-7<19-x
i)x+(x+1)+(x+2)+(x+3)+....+13+14=14
j)25+24+23+...+x+(x-2)+(x-3)=25
Câu 2:
a) (x-3).(y+5)=-17
b) (x+1).(xy-2)=11
c) xy-7x+y=-22
d) xy-3x+y=-20
Câu 1:
a: =>-2x-x+17=34+x-25
=>-3x+17=x+9
=>-4x=-8
hay x=2
b: =>17x+16x+27=2x+43
=>33x+27=2x+43
=>31x=16
hay x=16/31
c: =>-2x-3x+51=34+2x-50
=>-5x+51=2x-16
=>-7x=-67
hay x=67/7
e: 3x-32>-5x+1
=>8x>33
hay x>33/8
Bài 2. Tìm x, biết :
a) 3x – 15 = 25 – 5x b) 3x - 17 = 2x – 7 c) 2x – 17 = – (3x – 18)
d) 3x – 14 = 2(x – 9) + 1 e) f) (x – 5)2 = 9
a) 3x – 15 = 25 – 5x
=> 3x + 5x = 25 + 15
=> 8x = 40
=> x = 5
b) 3x - 17 = 2x – 7
=> 3x - 2x = -7 + 17
=> x = 10
c) 2x – 17 = – (3x – 18)
=> 2x - 17 = -3x + 18
=> 2x + 3x = 18 + 17
=> 5x = 35
=> x = 7
d) 3x – 14 = 2(x – 9) + 1
=> 3x - 14 = 2x - 18 + 1
=> 3x - 2x = -18 + 1 + 14
=> x = -3
f) (x – 5)2 = 9
\(\Rightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)
a) Ta có: \(3x-15=25-5x\)
\(\Leftrightarrow3x-15-25+5x=0\)
\(\Leftrightarrow8x-40=0\)
\(\Leftrightarrow8x=40\)
hay x=5
Vậy: x=5
b) Ta có: \(3x-17=2x-7\)
\(\Leftrightarrow3x-17-2x+7=0\)
\(\Leftrightarrow x-10=0\)
hay x=10
Vậy: x=10
c) Ta có: \(2x-17=-\left(3x-18\right)\)
\(\Leftrightarrow2x-17=-3x+18\)
\(\Leftrightarrow2x-17+3x-18=0\)
\(\Leftrightarrow5x-35=0\)
\(\Leftrightarrow5x=35\)
hay x=7
Vậy: x=7
d) Ta có: \(3x-14=2\left(x-9\right)+1\)
\(\Leftrightarrow3x-14=2x-18+1\)
\(\Leftrightarrow3x-14-2x+18-1=0\)
\(\Leftrightarrow x+3=0\)
\(\Leftrightarrow x=-3\)
Vậy: x=-3
f) Ta có: \(\left(x-5\right)^2=9\)
\(\Leftrightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)
Vậy: \(x\in\left\{2;8\right\}\)
Bài 2. Tìm x, biết :
a) \(3x-15=25-5x\)
\(\Leftrightarrow8x=40\)
\(\Leftrightarrow x=5\)
Vậy x = 5
b) \(3x-17=2x-7\)
\(\Leftrightarrow x=10\)
Vậy x = 10
c) \(2x-17=-\left(3x-18\right)\)
\(\Leftrightarrow2x-17=18-3x\)
\(\Leftrightarrow5x=35\)
\(\Leftrightarrow x=7\)
Vậy x = 7
d) \(3x-14=2\left(x-9\right)+1\)
\(\Leftrightarrow3x-14=2x-18+1\)
\(\Leftrightarrow3x-14=2x-17\)
\(\Leftrightarrow x=-3\)
Vậy x = -3
e) \(\left(x-5\right)^2=9\)
\(\Rightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)
Vậy x = {8; 2}
a) 5x – 65 = 5.32
b) 200 – (2x + 6) = 43
c) 2(x−51) = 2.23 + 20
d) 135 – 5(x + 4) = 35
e) (2x – 4)(15 – 3x) = 0
f) 2x+1.22014 = 22016
g) 15+(x−1)3=42
h)15 – x = 17+ (−9)
i) | x − 5| = |−7|+(−4)
k) | x − 3| − 12= −9+ | −7|
a) \(5x-65=5.3^2 \\ 5x-65=45\\5x=45+65\\5x=110\\x=22\)
b) \(200-(2x+6)=4^3\\2x+6=200-4^3\\2x+6=136\\2x=130\\x=65\)
c) \(2(x-51)=2.2^3+20\\2(x-51)=16+20\\2(x-51)=36\\x-51=18\\x=51+18=69\)
d) \(135-5(x+4)=35\\5(x+4)=135-45\\5(x-4)=90\\x-4=18\\x=18+4=22\)
e) \((2x-4)(15-3x)=0\\2(x-2).3(5-x)=0\\(x-2)(5-x)=0\\ \left[ \begin{array}{l}x-2=0\\5-x=0\end{array} \right. \\ \left[ \begin{array}{l}x=2\\x=5\end{array} \right.\)
f) \(2^{x+1} . 2^{2014}=2^{2016} \\ (2^{x+1} . 2^{2014}):2^{2014}=2^{2016} :2^{2014} \\ 2^{x=1}=2^{2016-2014} \\2^{x+1}=2^2\\x+1=2\\x=1\)
g) \(15+(x-1)^3=43\\(x-1)^3=15-42\\(x-1)^3=-27\\(x-1)^3=(-3)^3\\x-1=-3\\x=-2\)
h) \(15-x=17+(-9)\\15-x=17-9\\15-x=8\\x=15-8\\x=7\)
i) \(|x-5|=|-7|+|-4|\\|x-5|=7+4\\|x-5|=11\\ \left[ \begin{array}{l}x-5=11\\x-5=-11\end{array} \right. \\ \left[ \begin{array}{l}x=16\\x=-6\end{array} \right.\)
k) \(|x-3|-12=-9+|-7|\\|x-3|-12=-9+7\\|x-3|-12=-2\\|x-3|=10 \\ \left[ \begin{array}{l}x-3=10\\x-3=-10\end{array} \right. \\ \left[ \begin{array}{l}x=13\\x=-7\end{array} \right.\)
Bài 2.Tìm x
a,17-3x-11=31-2x
b,12-|x+3|=5
c,4x+(-46)= -30
d,-20+(5x-5)=60
10+|1-2x|=15
a,17-3x-11=31-2x
=> 6 - 3x = 31 - 2x
=> 6 - 31 = - 2x + 3x
=> x = - 25
Vậy x = - 25
b,12 - | x + 3 |=5
=> | x + 3 | = 7
\(\Rightarrow\orbr{\begin{cases}x+3=7\\x+3=-7\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=4\\x=-10\end{cases}}\)
Vậy \(x\in\left\{4;-10\right\}\)
c,4 x+ (-46) = -30
=> 4x = - 30 + 46
=> 4x = 16
=> x = 4
Vậy x = 4
d, -20 + (5x - 5 ) = 60
= > - 20 + 5x - 5 = 60
=> 5x = 60 + 20 + 5
=> 5x = 85
=> x = 17
Vậy x = 17
e, 10 + |1 - 2x |= 15
=> | 1 - 2x | = 5
\(\Rightarrow\orbr{\begin{cases}1-2x=5\\1-2x=-5\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}2x=-4\\2x=6\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-2\\x=3\end{cases}}\)
Vậy \(x\in\left\{-2;3\right\}\)
Dài qua lần sau đừng đăng nhiều như v
Tự nghĩ k đc à
@@ Học tốt @@
## Chiyuki Fujito
Tìm x biết:
a. x-(17-8)=5+(10-3x)
b. 25-(30+x)=x-(27-8)
c. (x-12)-15=(20-7)-(18+x)
a. x - (17 - 8) = 5 + (10 - 3x)
=> x - 9 = 5 + 10 - 3x
=> x + 3x = 15 + 9
=> 4x = 24
=> x = 6
b. 25 - (30 + x) = x - (27 - 8)
=> 25 - 30 - x = x - 19
=> -x -x = -19 + 30 - 25
=> -2x = -14
=> x = 7
c. (x - 12) - 15 = (20 - 7) - (18 + x)
=> x - 12 - 15 = 13 - 18 - x
=> x + x = 13 - 18 + 12 + 15
=> 2x = 22
=> x = 11
1 Thực hiện phép tính bằng cách hợp lí.
a)(27-514)-(486-73)
b) -23.57+23.(-43)
c) 33.(17-15)-17.(33-5)
d) 1-3+5-7+...+17-19
2: tìm số nguyên x sao cho:
a)(1-x)3 = -8
b) 3x-4 chia hết cho x+3