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\(-\frac{3}{7}\left(x-7\right)-\left(-\frac{5}{14}\right)\left(2x-3\right)-15=\frac{7}{-21}\)
\(\Leftrightarrow-\frac{3}{7}\left(x-7\right)+\frac{5}{14}\left(2x-3\right)=\frac{44}{3}\)
\(\Leftrightarrow-\frac{3}{7}x+3+\frac{5}{7}x-\frac{15}{14}=\frac{44}{3}\)
\(\Leftrightarrow x\left(-\frac{3}{7}+\frac{5}{7}\right)+3-\frac{15}{14}=\frac{44}{3}\)
\(\Leftrightarrow x\frac{2}{7}+3=\frac{661}{42}\)
\(\Leftrightarrow x\frac{2}{7}=\frac{535}{42}\Leftrightarrow x=\frac{535}{12}\)
13/15 - (13/21 + x) . 7/12 = 7/10
=> (13/21 + x). 7/12 = 13/15 - 7/10
=> (13/21 + x) . 7/12 = 1/6
=> 13/21 + x = 1/6 : 7/12
=> 13/21 + x = 2/7
=> x = 2/7 - 13/21
=> x = -1/3
a, -15 - (x-7)= -21
-15-x +7=-21
-8-x=-21
-x=-13
x=13
b,(17-x)-12=0
17-x-12=0
5-x=0
x=5
=.= hk tốt!!
a,11-(15+21)=x-(25-9)
11-15-21=x-25+9
-x=-25+9-11+15+21
-x=9
x=-9
b,9-25=(7-x)-(25+7)
-16=7-x-32
x=7-32+16
x=-9
1,15-(x-7)=-21
x-7=15-(-21)
x-7= 36
x =36+7
x = 43
2,3x+17=2
3x =2-17
3x = -15
x = -15:3
x = -5
3,45-(x-9)=-35
x-9=45-(-35)
x-9=80
x=80+9
x=89
4,(-5)+x=15
x=15-(-5)
x=20
5,2x-(-17)=15
2x+17=15
2x=15-17
2x=-2
x=-2:2
x=-1
3/-7=13
o l m . v n
Toán lớp 6
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Lê Hà Vy 24 tháng 4 2016 lúc 18:05
Báo cáo sai phạm
1,15-(x-7)=-21
x-7=15-(-21)
x-7= 36
x =36+7
x = 43
2,3x+17=2
3x =2-17
3x = -15
x = -15:3
x = -5
3,45-(x-9)=-35
x-9=45-(-35)
x-9=80
x=80+9
x=89
4,(-5)+x=15
x=15-(-5)
x=20
5,2x-(-17)=15
2x+17=15
2x=15-17
2x=-2
x=-2:2
x=-1
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Gợi ý cho bạn
tìm x,biết
5-x-16=40+x
4x-10=15-x
15-x=4x-5
x-15=6+4x
-12+x=5x-20
7x-4=20+3x
5x-7=-21-2x
x+15=20-4x
17-x=7-6x
\(43+\left(9-21\right)=317\left(x+317\right)\)
\(\Rightarrow317-\left(x+317\right)=43+\left(9-21\right)\)
\(\Rightarrow317-\left(x+317\right)=43+\left(-12\right)\)
\(\Rightarrow317-\left(x+317\right)=31\)
\(\Rightarrow x+317=317-31\)
\(\Rightarrow x+317=286\)
\(\Rightarrow x=286-317\)
\(\Rightarrow x=-31\)
Vay x = -31
\(b.\left(15-x\right)+\left(x-12\right)=7-\left(-5+x\right)\)
\(\Rightarrow15-x+x-12=7+5+x\)
\(\Rightarrow15-12=12-x\)
\(\Rightarrow3=12-x\)
\(\Rightarrow12-x=3\)
\(\Rightarrow x=12-3\)
\(\Rightarrow x=9\)
Vay x = 9
....
a) 43+(9-21) = 317-(x+317)
43+(-12) = 317-(x+317)
317-(x+317) = 31
x+317 = 317-31=286
x = 286-317=(-31)
Tạm thời câu b mình chưa nghĩ ra nha.
15-(x-7)=-21
x-7=15+21
x-7=36
x=36+7
x=43
ủng hộ mk nhé
15-(x-7)=-21
x-7=15-(-21)
x-7=36
x =36+7
x=43
Ủng hộ mk nha ^...^
15 - ( x - 7 ) = -21
x - 7 = 15 - ( -21 )
x - 7 = 15 + 21
x - 7 = 36
x = 36 + 7
x = 43
nha bạn
^_^
15-(x-7)=-21
x-7=15-(-21)
x-7=36
x =36+7
x =43
T ủng hộ mk nhé ^...^ ^_^
\(15-\left(x-7\right)=-21\)
\(x-7=15-\left(-21\right)\)
\(x-7=36\)
\(x=36+7\)
\(x=43\)
\(15-\left(x-7\right)=-21\)
\(\Rightarrow x-7=15-\left(-21\right)\)
\(\Rightarrow x-7=36\)
\(\Rightarrow x=43\)
t nha