a) (x-4) : 6 - 5 = 0
b) 170 - ( 4 + 5 x ) = 101
c) 200 - ( 8x + 7 ) = 121
d) (x + 120 ) : 20 = 80
g) 450 : ( 50 - 7x ) = 30
1. Tìm x
a) (x - 7) + 5 = 16
b) 4 : x - 34 = 6
c) 120 : ( x - 1 ) + 3 = 23
d) 170 - ( x-7) : 5 = 20
e) x + 12 + 2 .x + 3 = 4.x + 3
a) (x - 7) + 5 = 16
=> x - 7 = 11
=> x = 18
b) 4 : x - 34 = 6
=> 4 : x = 40
=> x = \(\frac{1}{10}\)
c) 120 : ( x - 1 ) + 3 = 23
=> 120 : ( x - 1 ) = 20
=> x - 1 = 6
=> x = 7
d) 170 - ( x-7) : 5 = 20
=> ( x - 7 ) : 5 = 150
=> x - 7 = 750
=> x = 757
e) x + 12 + 2 .x + 3 = 4.x + 3
=> 3x + 17 = 4x + 3
=> x = 15
\(a,x-7=11\)
\(x=18\)
\(b,x-36=\frac{2}{3}\)
\(x=\frac{110}{3}\)
\(c,120:\left(x-1\right)=20\)
\(x-1=6\)
\(x=7\)
\(d,\left(x-7\right):5=150\)
\(x-7=10\)
\(x=17\)
\(d,x+12+2.x+3-4.x-3=0\)
\(x.\left(1+2-4\right)+3-3+12=0\)
\(x.\left(-1\right)+12=0\)
\(x.\left(-1\right)=-12\)
\(x=12\)
a) (x - 7) + 5 = 16
x - 7 = 16 - 5
x - 7 = 11
x = 11 + 7
x = 18
b) 4 : x - 34 = 6
4 : x = 6 + 34
4 : x = 40
x = 4 : 40
x = 1/10
c) 120 : ( x - 1 ) + 3 =23
120 : ( x - 1 ) = 23 +3
120 : ( x - 1 ) =26
x -1 = 120 :26
x - 1 =13/60
x = 13/60 + 1
x = 73/60
d) 170 - ( x - 7 ) :5 =20
170 - ( x - 7 ) = 20:5
170 - ( x - 7 ) =4
x- 7 = 170 - 4
x - 7 = 166
x = 166 + 7
x = 173
còn câu e mik ko bt làm nhé mà k cho mik nhé
2 * x - 7 = 15
4 * x + 5 = 205
80 / ( x + 1 ) = 40
72 - ( 2 * x - 4 ) = 2
75 - 5 ( x + 3 ) = 5
200 - 5 { 50 - [ 30 - ( 2 * x - 6 ) ] } = 100
408 -4 [ 200 -5 ( 3 * x - 19 ) ] = 8
7 * x : 7 = 4
7 * x + 9 * x - 20 = 12
20 : ( x - 5 ) = 20
9 * ( 2 * x - 8 ) = 0
2080 : 4 * x = 40
mk cần gấp ai đầu tiên mk tik cho n do
X2x—7=15
2x=15+7
2x=22
x=22:2
x=11
4x +5=205
4x=205–5
4x=200
x=200:4
x=50
80/(x+1)=40
==> 80: x+1=40
80:x=40-1
80:x=39
x=80:39
x=80/39
72–(2x—4)=2
2x—4=72-2
2x—4=70
2x=70+4
2x=74
x=74:2
x=37
75-5(x+3)=5
5(x+3)=75–5
5(x+3)=70
x+3=70:5
x+3=14
x=14–3
x=11
7x:7=4
7x=4.7
7x=28
x=28:7
x=4
20:(x—5)=20
x—5=20:20
x—5=1
x=1+5
x=6
9(2x—8)=0
2x=0:9
2x=0
x=0:2
x=0
2080:4x=40
4x=2080:40
4x=52
x=52:4
x=13
mik chỉ giải một nửa thôi nha,mệt lắm rồi
4*x+5=205
4*x = 205-5
4*x = 200
x = 200/4
x = 50
80/(x+1)=40
x+1 =80/40
x+1 =2
x =2-1
x =1
72-(2*x-4) =2
2*X-4 =72-2
2*X-4 =70
2*X =70+4
2*X =74
X =74/2
X =37
x2-4x+7 = 0 ⇔ x2 -4x + 4 + 3 = 0
⇔ (x-2)2+3=0 ⇔ (x-2)2=-3 (vô lí)
Vậy pt vô nghiệm
*Chứng minh phương trình \(x^2-4x+7=0\) vô nghiệm
Ta có: \(x^2-4x+7=0\)
\(\Leftrightarrow x^2-4x+4+3=0\)
\(\Leftrightarrow\left(x-2\right)^2+3=0\)
mà \(\left(x-2\right)^2+3\ge3>0\forall x\)
nên \(x\in\varnothing\)(đpcm)
giải phương trình:
\(\frac{x^2+4x+6}{x+2}-\frac{x^2+6x+12}{x+3}=\frac{x^2+8x+20}{x+4}-\frac{x^2+10x+30}{x+5}-\frac{4}{x^2+7x+12}\)
ko biết ok
Tính (theo mẫu):
Mẫu: 5 x (10 – 4)
Cách 1:
5 x (10 – 4) = 5 x 6 = 30
Cách 2:
5 x (10 – 4) = 5 x 10 – 5 x 4 = 50 – 20 = 30
a) 3 x (20 – 5)
b) 20 x (40 – 1)
Hướng dẫn giải:
a) 3 x (20 – 5)
Cách 1:
3 x (20 – 5) = 3 x 15 = 45
Cách 2:
3 x (20 – 5) = 3 x 20 – 3 x 5 = 60 – 15 = 45
b) 20 x (40 – 1)
Cách 1:
20 x (40 – 1) = 20 x 39 = 780
Cách 2:
20 x (40 – 1) = 20 x 40 – 20 x 1 = 800 – 20 = 780
Tìm x
x - 4/5 = 3/7
x + 3/7 = 4/5
19/20 - x = 8/5 - 3/4
4/5 x X = 6/9 - 4/7
x : 7/9 = 6/8
2/3 - x/6 = 6/18
a: x-4/5=3/7
=>x=3/7+4/5=43/35
b: x+3/7=4/5
=>x=4/5-3/7=13/35
c: 19/20-x=8/5-3/4
=>19/20-x=32/20-15/20=17/20
=>x=2/20=1/10
d: =>4/5*x=2/21
=>x=2/21:4/5=5/42
e: =>x:7/9=6/8
=>x=6/8*7/9=3/4*7/9=21/36=7/12
f: =>x/6=2/3-1/3=1/3
=>x=2
Tìm x
x - 4/5 = 3/7
x + 3/7 = 4/5
19/20 - x = 8/5 - 3/4
4/5 x X = 6/9 - 4/7
x : 7/9 = 6/8
2/3 - x/6 = 6/18
a: x-4/5=3/7
=>x=3/7+4/5=43/35
b: x+3/7=4/5
=>x=4/5-3/7=13/35
c: 19/20-x=8/5-3/4
=>19/20-x=32/20-15/20=17/20
=>x=2/20=1/10
d: =>4/5*x=11/21
=>x=55/84
e: =>x=6/8*7/9=42/72=7/12
f: =>x/6=2/3-1/3=1/3
=>x=2
Giải các phương trình sau:
\(\frac{3}{4x-20}-\frac{15}{2x^2-50}+\frac{7}{6x+30}=0\)
\(\frac{8x^2}{3-12x^2}+\frac{1+8x}{4+8x}=\frac{-2x}{3-6x}\)
\(\frac{1}{x^2-2x+1}+\frac{1}{x^2+2x=1}=\frac{2}{x^2-1}\)
\(\frac{1}{x^2+1}+\frac{1}{x^2+3x+2}+\frac{1}{x^2+5x+6}+\frac{1}{x^2+7x+12}=\frac{4}{5}\)
giải phương trình:
a)(x-5)^2+3(x-5)=0
b)2x-1/3-5x+2/7=x+13
c)x-1/x+2-x/x-2=7x-6/4-x^2
a, \(\left(x-5\right)\left(x-5+3\right)=0\Leftrightarrow x=5;x=2\)
b, \(-4x=\dfrac{274}{21}\Leftrightarrow x=-\dfrac{137}{42}\)
c, đk x khác - 2 ; 2
\(x^2-3x+2-x^2-2x=6-7x\Leftrightarrow-5x+2=6-7x\)
\(\Leftrightarrow2x-4=0\Leftrightarrow x=2\left(ktm\right)\)
Vậy pt vô nghiệm