(x-15):5+20=22
64+(20-3x)=75
[(6x-39):3].28=5628
400-[545-(45+x)]=0
(111:x+25):14=2
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(111:x+25):14=2
=> 111:x+25=2.14
=> 111:x+25=28
=> 111:x=28-25
=> 111:x=3
=> x=111:3
=> x=37
[(6x-39):3].28=5628
=> (6x-39):3=5628:28
=> (6x-39):3=201
=> 6x-39=201.3
=> 6x-39=603
=> 6x=603+39
=> 6x=642
=> x=642:6
=> x=107
400-[545-(45+x)]=0
=> 545-(45+x)=400-0
=> 545-45-x=400
=> 500-x=400
=> x=500-400
=> x=100
(111:x+25):14=2
111 : x + 25 = 2 . 14 = 28
111 : x = 28 - 25 = 3
x = 111 : 3
x = 37
[(6x-39):3] .28=5628
( 6x - 39 ) : 3 = 5628 : 28 = 201
6x - 39 = 201 . 3 = 603
6x = 603 + 39 = 642
x = 642 : 6
x = 107
400-[545-(45+x)]=0
545 - ( 45 + x )=400
45 + x = 545 - 400 = 145
x = 145 - 45
x = 100
1. 3y = 0
=> y = 0
2. 1+x = 0
<+ x = -1
3.
\(1-2t=0\)
\(\Leftrightarrow2t=1\)
\(\Leftrightarrow\dfrac{1}{2}\)
4. 2x +x + 3 =0
\(\Leftrightarrow3x+3=0\)
\(\Leftrightarrow x=-3\)
5.
\(25x-20=0\)
\(\Leftrightarrow25x=20\)
\(\Leftrightarrow x=\dfrac{4}{5}\)
7.
2x-3 = x+5
<=> 2x - x = 5+3
<=> x = 8
8.
x-8=2x+3
<=> x - 2x = 3+8
<=> -x = 11
<=> x = -11
9. 17-2x = 3x-5
<=> -2x-3x = -5-17
<=> -5x = -22
<=> x = \(\dfrac{22}{5}\)
10.
2x+x+22=0
<=> 3x+22=0
<=> 3x = -22
<=> x = \(\dfrac{-22}{3}\)
Mấy bài kia tự giải tương tự nhá!!!
\(o,x^2-9x+20=0\)
\(\Leftrightarrow x^2-4x-5x+20=0\)
\(\Leftrightarrow x\left(x-4\right)-5\left(x-4\right)=0\)
\(\Leftrightarrow\left(x-4\right)\left(x-5\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-4=0\\x-5=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=4\\x=5\end{cases}}\)
\(n,3x^3-3x^2-6x=0\)
\(\Leftrightarrow3x\left(x^2-x-2\right)=0\)
\(\Leftrightarrow3x\left(x^2+x-2x-2\right)=0\)
\(\Leftrightarrow3x\left[x\left(x+1\right)-2\left(x+1\right)\right]=0\)
\(\Leftrightarrow3x\left(x+1\right)\left(x-2\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}\orbr{\begin{cases}3x=0\\x+1=0\end{cases}}\\x-2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}\orbr{\begin{cases}x=0\\x=-1\end{cases}}\\x=2\end{cases}}\)
x+15=7+6x
15-7=6x-x
8=5x
x=8/5
vậy x=8/5
17-x=7-6x
17-7=-6x+x
10=-5x
x=10:(-5)
x=-2
Vậy x=-2
3x+(-21)=12-8x
3x+8x=12-(-21)
11x=33
x=33:11
x=3
vậy x=3
125:(3x-13)=25
3x-13=125:25
3x-13=5
3x=13+5
3x=15
x=15:3
x=5
Vậy x=5
541+(218-z)=735
218-z=735-541
218-z=194
z=218-194
z=24
(x-15):5+20=22
(x-15):5=22-20
(x-15):5=2
x-15=2x5
x-15=10
x=10+15
x=25
64+(20-3x)=75
20-3x=75-64
20-3x=11
3x=20-11
3x=9
x=9:3
x=3
[(6x-39):3].28=5628
(6x-39):3=5628:28
(6x-39):3=201
6x-39=201x3
6x-39=603
6x=603+39
6x=642
x=642:6
x=107
400-[545-(45+x)]=0
545-(45+x)=400-0
545-(45+x)=400
45+x=545-400
45+x=145
x=145-45
x=100
(111:x+25):14=2
111:x+25=2x14
111:x+25=28
111:x=28-25
111:x=3
x=111:3
x=37
a/ \(\Rightarrow\left(x-15\right):5=2\Rightarrow x-15=10\Rightarrow x=25\)
b/ \(\Rightarrow20-3x=11\Rightarrow3x=9\Rightarrow x=3\)
c/ => \(\left(6x-39\right):3=201\Rightarrow6x-39=603\Rightarrow6x=642\Rightarrow x=107\)
d/ \(\Rightarrow545-\left(45+x\right)=400\Rightarrow45+x=145\Rightarrow x=100\)
e/ \(\Rightarrow111:x+25=28\Rightarrow111:x=3\Rightarrow x=\frac{111}{3}\)