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`- 9 . ( x - 6 ) + 20 = 56`
`=> -9 . ( x - 6 ) = 56-20`
`=> -9 . ( x - 6 ) =36`
`=>x-6=36:(-9)`
`=>x-6=-4`
`=>x=-4+6`
`=>x=2`
`-------------`
` ( 245 - x ) + 7^2=149`
`=>( 245 - x ) +49=149`
`=> 245 - x =149-49`
`=> 245 - x =100`
`=>x=245-100`
`=>x=145`
`------------`
`(2^x-3).7=35`
`=> 2^x-3=35:7`
`=> 2^x-3=5`
`=>2^x=5+3`
`=>2^x=8`
`=>2^x=2^3`
`=>x=3`
2: \(=\dfrac{-2}{75}+\dfrac{5}{39}=\dfrac{33}{325}\)
3: \(=\dfrac{6}{11}\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{6}{11}\)
4: \(=\dfrac{7}{19}\left(\dfrac{5}{13}+\dfrac{8}{13}-1\right)=-2\cdot\dfrac{7}{19}=-\dfrac{14}{19}\)
5: \(=\dfrac{2}{7}\left(\dfrac{4}{23}-\dfrac{27}{23}+1\right)=0\)
6: \(=\dfrac{3}{8}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\dfrac{11}{8}=\dfrac{3}{8}+\dfrac{11}{8}=\dfrac{14}{8}=\dfrac{7}{4}\)
Ta có |x+3| >=0 với mọi x
=> |x-3|+11 >=11 hay A >=11
Dấu "=" xảy ra <=> |x-3|=0
<=> x-3=0
<=> x=3
Vậy MinA=11 đạt được khi x=3
A= \(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\)
= \(11\frac{3}{13}-2\frac{4}{7}-5\frac{3}{13}\)
= \(\left(11\frac{3}{13}-5\frac{3}{13}\right)-2\frac{4}{7}\)
= \(6-2\frac{4}{7}\)
= \(3\frac{3}{7}\)
B= \(\left(96\frac{4}{9}+3\frac{7}{11}\right)-4\frac{4}{9}\)
= \(96\frac{4}{9}+3\frac{7}{11}-4\frac{4}{9}\)
= \(\left(96\frac{4}{9}-4\frac{4}{9}\right)+3\frac{7}{11}\)
= \(92+3\frac{7}{11}\)
= \(95\frac{7}{11}\)
C= \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+1\frac{5}{7}\)
= \(\frac{-5}{7}.\left(\frac{2}{11}+\frac{9}{11}\right)+1\frac{5}{7}\)
= \(\frac{-5}{7}.1+1\frac{5}{7}\)
= \(\frac{-5}{7}+1\frac{5}{7}\)
= 1
(ý D bn tự làm ha)
mình vieetts ra thì dài lám
nếu bạn đã chác chăn về kiến thức thì hãy phân tích rồi tìm cách lam
còn ngược lại ban hãy tính máy tính rồi đoán cách làm cũng được
10 - [ 12 - ( -9 - 1 ) ]
= 10 - [ 12 - 9 + 1 ]
= 10 - 12 + 9 - 1
= 6
\(10-\left[12-\left(-9-1\right)\right]\)
\(=10-\left[12-\left(-10\right)\right]\)
\(=10-\left[12+10\right]\)
\(=10-22\)
\(=-12\)
\(\left(\dfrac{6:\dfrac{3}{5}-\dfrac{17}{16}.\dfrac{6}{7}}{\dfrac{21}{5}.\dfrac{10}{11}+\dfrac{57}{11}}-\dfrac{\left(\dfrac{3}{20}+\dfrac{1}{2}-\dfrac{1}{15}\right).\dfrac{12}{49}}{\dfrac{10}{3}+\dfrac{2}{9}}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\left(\dfrac{\dfrac{509}{56}}{9}-\dfrac{\dfrac{7}{12}.\dfrac{12}{49}}{\dfrac{32}{9}}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\left(\dfrac{509}{504}-\dfrac{\dfrac{1}{7}}{\dfrac{32}{9}}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\left(\dfrac{509}{504}-\dfrac{9}{224}\right).x=\dfrac{215}{96}\)
\(\Rightarrow\dfrac{1955}{2016}.x=\dfrac{215}{96}\)
\(\Rightarrow x=\dfrac{215}{96}:\dfrac{1955}{2016}\)
\(\Rightarrow x=\dfrac{903}{391}\)
`[ 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 ?
\(A,\dfrac{7}{11}+\dfrac{5}{6}-\dfrac{-4}{11}-\dfrac{1}{6}\)
\(= (\dfrac{7}{11}+\dfrac{-4}{11})-(\dfrac{5}{6}-\dfrac{1}{6})\)
\(=\dfrac{3}{11}-\dfrac{2}{3}\)
\(= \dfrac{9}{33}-\dfrac{22}{33}\)
\(= \dfrac{-13}{33}\)
\(B,\dfrac{5}{9}.\dfrac{7}{3}+\dfrac{5}{9}.\dfrac{9}{13}-\dfrac{5}{9}:\dfrac{13}{5}\)
\(=(\dfrac{5}{9}.\dfrac{5}{9}:\dfrac{5}{9}).\dfrac{7}{3}+\dfrac{9}{13}-\dfrac{13}{5}\)
\(=(\dfrac{5}{9}.\dfrac{7}{3})+(\dfrac{9}{13}-\dfrac{13}{5})\)
\(=(\dfrac{5}{9}.\dfrac{21}{9})+(\dfrac{45}{65}-\dfrac{169}{65})\)
\(=\dfrac{35}{27}+\dfrac{-124}{65}\)
\(=\dfrac{2275}{1755}+\dfrac{-3348}{1755}\)
\(=\dfrac{-1073}{1755}\)
(7x + 6) -11 = 9
7x + 6 = 11 + 9
7x + 6 = 20
7x = 20 - 6
7x = 14
x = 14 : 7
x = 2
Vậy x = 2
(7x+6)-11=9
7x+6=9+11
7x+6=20
7x=20-6
7x=14
x=14/7
x=2