x : 1/2 + x : 1/4 + x : 1/6 + x : 1/8 + x : 1/10 = 1

\(x\cdot2+x\cdot4+x\cdot6+x\cdot8+x\cdot10=1\)

\(x\cdot\left(2+4+6+8+10\right)=1\)

\(x\cdot30=1\)

\(x=\frac{1}{30}\)

Bài 1:

a. $(-20)+x=-30$

$x-20=-30$

$x=-30+20=-(30-20)=-10$

b.

$(-10)-x=-20$

$x=(-10)-(-20)=-10+20=20-10=10$

c. Đề sai. Bạn xem lại.

d.

$x+(-3)=-7$

$x=-7-(-3)=-7+3=-(7-3)=-4$

e.

$x-(-5)=-9$

$x=(-9)+(-5)=-14$

f.

$x(-11)=12$

$x=\frac{12}{-11}=\frac{-12}{11}$

h.

$2x-10=20$

$2x=20+10=30$

$x=30:2=15$

l.

$4x-8=-8$
$4x=-8+8=0$

$x=0:4=0$

k.

$-12-(-2)x=-8$

$(-2)x=-12-(-8)=-12+8=-(12-8)=-4$

$x=(-4):(-2)=2$

Bài 2:

a. $-20-(10-x)=-3$

$10-x=-20-(-3)=-20+3=-(20-3)=-17$

$x=10-(-17)=10+17=27$

b.

$14+(14-x)=-2$
$14-x=-2-14=-16$

$x=14-(-16)=14+16=30$

c.

$-15-(x-3)=-7$

$x-3=-15-(-7)=-15+7=-8$

x=-8+3=-5$

d.

$(x+4)+(-20)=-8$

$x+4=-8-(-20)=-8+20=12$
$x=12-4=8$

e.

$-2x-2=-4$

$-2x=-4+2=-2$

$x=(-2):(-2)=1$

f.

$-2x+4=-4$

$-2x=-4-4=-8$

$x=(-8):(-2)=4$

l.

$-12-(-2)x=-2-4=-6$

$(-2)x=-12-(-6)=-12+6=-6$

$x=(-6):(-2)=3$

tách ra

\(1\)) \(5-\left(10-x\right)=7\)
\(10-x=5-7\)
\(10-x=-2\)
\(x=10-\left(-2\right)\)
\(x=12\)

\(2\)) \(-32-\left(x-5\right)=0\)
\(x-5=-32-0\)
\(x-5=-32\)
\(x=-32+5\)
\(x=-27\)

1)10-x=5-7

x=10-(-2)

x=12

2)x+5=0+32

x=32-5

x=27

3) -12+2x-9+x=0

-12+(2x+x-9)=0

3x-9=0+12

3x=12+9

x=21:3

x=7

4) 15-x=1-11

x=15-(-10)

x=25

5) 4-(27+3)=x-9

4-30=x-9

-26+9=x

x=-17

1: 7-x=8+(-7)

=>7-x=8-7=1

=>x=7-1=6

2: \(x-8=\left(-3\right)-8\)

=>x-8=-11

=>\(x=-11+8=-3\)

3: \(2-x=10-9+23\)

=>\(2-x=33-9=24\)

=>x=2-24=-22

4: \(-2-x=15\)

=>\(x=-2-15=-17\)

5: \(-7+x-8=-3-1+13\)

=>x-14=13-4=9

=>x=9+14=23

6: 100-x+7=-x+3

=>107-x=3-x

=>107=3(vô lý)

7: \(23+x=8-2x\)

=>\(x+2x=8-23\)

=>3x=-15

=>x=-15/3=-5

`x-3/5 =-4/10`

`=>x=-4/10 + 3/5`

`=>x=-4/10 + 6/10`

`=>x= 2/10`

`=>x=1/5`

`----`

`(x-1)/(-2) = -8/(x-1)`

`=> (x-1).(x-1) = (-2).(-8)`

`=> (x-1)^2 = 16`

`=> (x-1)^2 = +- 4^2`

\(\Rightarrow\left[{}\begin{matrix}x-1=4\\x-1=-4\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=4+1\\x=-4+1\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=5\\x=-3\end{matrix}\right.\)

a) \(\dfrac{1}{2}+x=\dfrac{5}{6}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{2}=\dfrac{5}{6}-\dfrac{3}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)

b) \(x+\dfrac{1}{4}=\dfrac{3}{4}\)

\(\Rightarrow x=\dfrac{3}{4}-\dfrac{1}{4}=\dfrac{2}{4}=\dfrac{1}{2}\)

c) \(x-\dfrac{1}{5}=\dfrac{3}{10}\)

\(\Rightarrow x=\dfrac{3}{10}+\dfrac{1}{5}=\dfrac{3}{10}+\dfrac{2}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)

d) \(\dfrac{5}{6}-x=\dfrac{1}{3}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{3}=\dfrac{5}{6}-\dfrac{2}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)

e) \(\dfrac{3}{10}+x=\dfrac{1}{2}\)

\(\Rightarrow x=\dfrac{1}{2}-\dfrac{3}{10}=\dfrac{5}{10}-\dfrac{3}{10}=\dfrac{2}{10}=\dfrac{1}{5}\)

g) \(x+\dfrac{1}{4}=\dfrac{3}{8}\)

\(\Rightarrow x=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{3}{8}-\dfrac{2}{8}=\dfrac{1}{8}\)

a) ⇒x=56−12=56−36=26=13⇒x=56−12=56−36=26=13

b) ⇒x=34−14=24=12⇒x=34−14=24=12

c) ⇒x=310+15=310+210=510=12⇒x=310+15=310+210=510=12

d) ⇒x=56−13=56−26=36=12⇒x=56−13=56−26=36=12

e) ⇒x=12−310=510−310=210=15⇒x=12−310=510−310=210=15

g) ⇒x=38−14=38−28=18⇒x=38−14=38−28=18

Đọc tiếp

a) ⇒x=56−12=56−36=26=13⇒x=56−12=56−36=26=13

b) ⇒x=34−14=24=12⇒x=34−14=24=12

c) ⇒x=310+15=310+210=510=12⇒x=310+15=310+210=510=12

d) ⇒x=56−13=56−26=36=12⇒x=56−13=56−26=36=12

e) ⇒x=12−310=510−310=210=15⇒x=12−310=510−310=210=15

g) ⇒x=38−14=38−28=18⇒x=38−14=38−28=18

a) -10 - (x - 5) + (3 - x) = -8

=> -10 - x + 5 + 3 -x = -8

=> -2x - 2 = -8

=> -2x = -6

=> x = -6/-2 = 3

b) 10 + 3(x - 1) = 10 + 6x

=> 10 + 3x - 3 = 10 + 6x

=> 3x - 6x = 10 - 7

=> -3x = 3

=> x = 3/-3 = -1

c) (x + 1)(x  - 2) = 0

=> \(\orbr{\begin{cases}x+1=0\\x-2=0\end{cases}}\)

=> \(\orbr{\begin{cases}x=-1\\x=2\end{cases}}\)