Tìm x
A, X/1<7/57 b,15/11<x/5. c,x/15=2/5. d,1/7=3/x
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a) \(\dfrac{4}{7}\times x=\dfrac{5}{9}+\dfrac{1}{5}=\dfrac{34}{45}\)
\(x=\dfrac{34}{45}:\dfrac{4}{7}=\dfrac{119}{90}\)
b) \(\dfrac{11}{15}:x=\dfrac{2}{3}-\dfrac{9}{15}=\dfrac{1}{15}\)
\(x=\dfrac{11}{15}:\dfrac{1}{15}=11\)
a) 4/7 x X - 1/5 = 5/9
4/7 x X = 5/9 + 1/5
4/7 x X = 34/45
X = 34/45 : 4/7
X = 119/90
b)9/15 + 11/15 : X = 2/3
11/15 : X = 2/3 - 9/15
11/15 : X = 1/15
X = 11/15 : 1/5
X = 11
a, -15 + \(x\) = -14 - (-57)
-15 + \(x\) = -14 + 57
\(x\) = -14 + 57 + 15
\(x\) = 58
b, (-14) + \(x\) - 7 = -10
\(x\) = -10 + 7 + 14
\(x\) = -3 + 14
\(x\) = 11
\(\left(\dfrac{6:\dfrac{3}{5}-\dfrac{17}{16}.\dfrac{6}{7}}{\dfrac{21}{5}.\dfrac{10}{11}+\dfrac{57}{11}}-\dfrac{\left(\dfrac{3}{20}+\dfrac{1}{2}-\dfrac{1}{15}\right).\dfrac{12}{49}}{\dfrac{10}{3}+\dfrac{2}{9}}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\left(\dfrac{\dfrac{509}{56}}{9}-\dfrac{\dfrac{7}{12}.\dfrac{12}{49}}{\dfrac{32}{9}}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\left(\dfrac{509}{504}-\dfrac{\dfrac{1}{7}}{\dfrac{32}{9}}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\left(\dfrac{509}{504}-\dfrac{9}{224}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\dfrac{1955}{2016}.x=\dfrac{215}{96}\)
\(\Rightarrow x=\dfrac{215}{96}:\dfrac{1955}{2016}\)
\(\Rightarrow x=\dfrac{903}{391}\)
`[ 6 : 3/5 - 17/16 . 6/7 : 21/5 . 10/11 + 57/11 - (3/20 + 1/2 - 1/15) . 12/49 : 10/3 + 2/9 ] . x = 215/96`
`=>[ 6 . 5/3 - 17/16 . 6/7 . 5/21 . 10/11 + 57/11 - (3/20 + 1/2 - 1/15) . 12/49 . 3/10 + 2/9 ] . x = 215/96`
`=>[10- 51/56 . 6/7 . 5/21 . 10/11 + 57/11 - (3/20 + 1/2 - 1/15) . 12/49 . 3/10 + 2/9 ] . x = 215/96`
`=> [10- 153/196 . 5/21 . 10/11 + 57/11 - (3/20 + 1/2 - 1/15) . 12/49 . 3/10 + 2/9 ] . x = 215/96`
`=> [10- 255/1372 . 10/11 + 57/11 - (3/20 + 1/2 - 1/15) . 12/49 . 3/10 + 2/9 ] . x = 215/96`
`=> [10- 1275/7546 + 57/11 - (3/20 + 1/2 - 1/15) . 12/49 . 3/10 + 2/9 ] . x = 215/96`
`=> (10- 1275/7546 + 57/11 - 7/12. 12/49 . 3/10 + 2/9 ) . x = 215/96`
`=> ( 10- 1275/7546 + 57/11 -343/600 . 3/10 + 2/9 ) . x = 215/96`
`=> ( 10- 1275/7546 + 57/11 -343/2000 + 2/9 ) . x = 215/96`
`=>15,06357671 . x= 215/96`
`=> x= 215/96: 15,06357671`
`=>x= 0,1486754027`
Đề có phải như vậy không nhỉ ?
A=77+105+161
TA THẤY 77 CHIA HẾT CHO 7
105 CHIA HẾT CHO 7
161 CHIA HẾT CHO 7
NÊN ĐỂ A CHIA HẾT CHO 7 THÌ X CŨNG PHẢI CHIA HẾT CHO 7 => X THUỘC 7K
NGƯỢC LẠI NẾU ĐỂ A KHÔNG CHIA HẾT CHO 7 => X KHÁC 7K