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1) 5.( x - 6 ) - 2.( x + 9 ) = 21
5x - 30 - 2x - 18 = 21
3x - 48 = 21
3x = 21 + 48
3x = 69
x = 23
2) 2.( x + 3 ) + 3.( x + 1 ) = 15 - ( - 9 )
2x + 6 + 3x + 3 = 24
5x + 9 = 24
5x = 24 - 9
5x = 15
x = 3
3) ( - x + 5 ).(3 - x ) = 0
=> - x + 5 = 0 hoặc 3 - x = 0
=> x = 5 hoặc x = 3
4) ( x - 12 ) - 15 = ( 20 - 7 ) - ( 18 + x )
x - 12 - 15 = 13 - 18 - x
x - 27 = - 5 - x
x + x = - 5 + 27
2x = 22
x = 11
5) x - ( 17 - 8 ) = 5 + ( 10 - 3x )
x - 9 = 5 + 10 - 3x
x + 3x = 15 + 9
4x = 24
x = 6
a, \(\dfrac{3}{15}-x=-\dfrac{1}{7}\Leftrightarrow\dfrac{21-105x}{105}=\dfrac{-15}{105}\Rightarrow-105x=-36\)
\(\Leftrightarrow x=\dfrac{36}{105}=\dfrac{12}{35}\)
b, \(\left(4,5+\dfrac{3}{4}x\right):\dfrac{8}{3}=\dfrac{9}{3}\Leftrightarrow\dfrac{45}{10}+\dfrac{3x}{4}=\dfrac{72}{9}=8\)
\(\Leftrightarrow\dfrac{36}{4}+\dfrac{3x}{4}=\dfrac{32}{4}\Rightarrow3x=-4\Leftrightarrow x=-\dfrac{4}{3}\)
c, mình ko hiểu đề lắm
(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 0)x( 9 - 8 + 7 - 6 + 5 - 4 - 3 + 2 - 1)x( 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 ×9)x()= 0 (vì 1-1+2-2+3+4-7 =0 )
Vì : 7.|x-y|^9+9.|x+2|^7 đều >= 0
=> VT >= 0 = VP
Dấu "=" xảy ra <=> x-y=0 và x+2=0 <=> x=y=-2
Vậy x=y=-2
Tk mk nha
Ta có : \(\frac{4}{11}.\frac{-2}{9}+\frac{4}{11}\frac{-8}{9}+\frac{4}{11}.\frac{1}{9}\)
= \(\frac{4}{11}.\left(\frac{-2}{9}+\frac{-8}{9}+\frac{1}{9}\right)\)
= \(\frac{4}{11}.\frac{-9}{9}\)
= \(\frac{4}{11}.\left(-1\right)\)
= \(\frac{-4}{11}\)
\(\frac{4}{11}\left(-\frac{2}{9}+-\frac{8}{9}+\frac{1}{9}\right)=\frac{4}{11}1=\frac{4}{11}\)
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
a) \(x.9,1+x.1,9=26,4\)
\(\Rightarrow x.\left(9,1+1,9\right)=26,4\)
\(\Rightarrow x.11=26,4\)
\(\Rightarrow x=\dfrac{26,4}{11}=\dfrac{12}{5}\)
Vậy \(x=\dfrac{12}{5}\)
b) \(x.9,9+x:10=12,5\)
\(\Rightarrow x.9,9+x.\dfrac{1}{10}=12,5\)
\(\Rightarrow x.\left(9,9+\dfrac{1}{10}\right)=12,5\)
\(\Rightarrow x.10=12,5\)
\(\Rightarrow x=\dfrac{12,5}{10}=\dfrac{5}{4}\)
Vậy \(x=\dfrac{5}{4}\)
c) \(x:0,1-x:4-x.0,75=2,25\)
\(\Rightarrow x.\dfrac{1}{0,1}-x.\dfrac{1}{4}-x.0,75=2,25\)
\(\Rightarrow x.10-x.\dfrac{1}{4}-x.0,75=2,25\)
\(\Rightarrow x.\left(10-\dfrac{1}{4}-0,75\right)=2,25\)
\(\Rightarrow x.9=2,25\)
\(\Rightarrow x=\dfrac{2,25}{9}=\dfrac{1}{4}\)
Vậy \(x=\dfrac{1}{4}\)
d) \(x:0,25-x=51,6\)
\(\Rightarrow x.\dfrac{1}{0,25}-x=51,6\)
\(\Rightarrow x.4-x=51,6\)
\(\Rightarrow x.\left(4-1\right)=51,6\)
\(\Rightarrow x.3=51,6\)
\(\Rightarrow x=\dfrac{51,6}{3}=\dfrac{86}{5}\)
Vậy \(x=\dfrac{86}{5}\)
1: =-2/9(15/17+2/17)=-2/9
2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)
=-2-7/30=-67/30
3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
1: =-2/9(15/17+2/17)=-2/9
2: =−63+−2190=−63+−2190
=-2-7/30=-67/30
3: =34⋅75+97⋅32=34⋅75+97⋅32
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
Đáp án là : 0
Tk nha!!
9 x 9 x 9 x 9 x 9 x 9 x 9 x 9 x 9 x 9 x 9 x 9 x 9 x 9 x 1 x 1 x 5 x 8 x 5 x 4 x 0 x 2 x 4 x 3 x 6 = 0
Blink chính hãng nhé!
_Học_tốt_