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a) `123 - 27 + 27 + 13 - 123`
`= (123 - 123) + (27 - 27) + 13`
`= 0 + 0 + 13`
`= 13`
`---`
b) `175 + 25 + 13 + 15 - 175 - 25`
`= (175-175)+(25-25)+25+13`
`=0+0+25+13`
`=28`
`---`
c) \(53\times39+47\times39+53\times21+47\times21\)
\(=\text{[}\left(53+47\right)\times39]+\left[\left(53+47\right)\times21\right]\)
\(=\left(100\times39\right)+\left(100\times21\right)\)
\(=3900+2100\)
`=6000`
`---`
d) \(49\times35+49\times16-49\times61\)
`=` \(49\times\left(35+16-61\right)\)
`=` \(49\times\left(-10\right)\)
`=-490`
a) A=(135-35).(-47)+53.(-48-52)
= 100.(-47) + 53.(-100)
= 100.(-47) + (-53).100
= 100.(-47+-53)
= 100.(-100)
= -10000
\(x-\left\{57-\left[42+\left(-23-x\right)\right]\right\}=13-\left\{47+\left[25-\left(32-x\right)\right]\right\}\)
=>\(x-\left\{57-42+23+x\right\}=13-47-25+32-x\)
=>\(x-\left(x+38\right)=-27-x\)
=>\(-27-x=-38\)
=>x+27=38
=>\(x=38-27=11\)
\(x-\left\{57-\left[42+\left(-23-x\right)\right]\right\}=13-\left\{47+\left[25-\left(32-x\right)\right]\right\}\)
\(\Leftrightarrow x-57+42-23-x=13-47-25+32-x\)
\(\Leftrightarrow x-x-57+42-23=-27-x\)
\(\Leftrightarrow-57+42-23=-27-x\)
\(\Leftrightarrow-38=-27-x\)
\(\Leftrightarrow x=\left(-27\right)-\left(-38\right)\)
\(\Leftrightarrow x=11\)
Vậy \(x=11\) là giá trị cần tìm
\(x-\left(57-\left(42+\left(-23-x\right)\right)\right)=13-\left(47+\left(25-\left(32-x\right)\right)\right)\)
\(\Leftrightarrow\) \(x-\left(57-\left(42-23-x\right)\right)=13-\left(47+\left(25-32+x\right)\right)\)
\(\Leftrightarrow\) \(x-\left(57-42+23+x\right)=13-\left(47+25-32+x\right)\)
\(\Leftrightarrow\) \(x-57+42-23-x=13-47-25+32-x\)
\(\Leftrightarrow\) \(-38=-27-x\) \(\Leftrightarrow\) \(-x=-38+27=-11\Leftrightarrow x=11\)
vậy \(x=11\)
\(x-\left\{57-\left[42+\left(-23-x\right)\right]\right\}=13-\left\{47+\left[25-\left(32-x\right)\right]\right\}\)
\(\Leftrightarrow x-57+42-23-x=13-47-25+32-x\)
\(\Leftrightarrow x-x-57+42-23=-27-x\)
\(\Leftrightarrow-57+42-23=-27-x\)
\(\Leftrightarrow-38=-27-x\)
\(\Leftrightarrow x=-27-\left(-38\right)\)
\(\Leftrightarrow x=11\left(TM\right)\)
Vậy \(x=11\) là giá trị cần tìm
\(\Leftrightarrow\) \(x-\left(57-\left(42-23-x\right)\right)=13-\left(47+\left(25-32+x\right)\right)\)
\(\Leftrightarrow\) \(x-\left(57-42+23+x\right)=13-\left(47+25-32+x\right)\)
\(\Leftrightarrow\) \(x-57+42-23-x=13-47-25+32-x\)
\(\Leftrightarrow\) \(-38=-27-x\) \(\Leftrightarrow\) \(-x=-38+27=-11\Leftrightarrow x=11\)
vậy \(x=11\)
a, 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
= 53 x (39-21) + 47 x (93-21)
=53 x 18 + 47 x 18
= (53 +47) x 18
=100 x 18
=1800
b,2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
=24 x 53 + 24 x 87 - 24 x 40
=24 x (53+87-40)
=24 x 100
=2400
c,5 x 7 x 77 - 7 x 60 +49 x 25 -15 x 42.
=5 x 7 x 77 - 7 x 5 x 12 +49 x 5 x 5 - 5 x 3 x 42.
=5 x 539 - 84 x 5 +245 x 5 -5 x 126
=5 x (539 - 84 +245 -126)
=5 x 574
=2870
=>x-57+42-23-x=13-47-25+32-x
=>x-x-57+42-23=-27-x
=>-57+42-23=-27-x
=>-38=-27-x
=>x=-27-(-38)
=>x=11
x-57+42-23-x=13-47-25+32-x
x=13-47-25+32+23-42+57
x=11
tick nha bạn
c) !2-x!+2=x
!x-2!=x-2
đúng với mọi x>=2
Tập ghi có dấu đi bạn ei
ghi như thế méo ai hiểu đâu
và......kết bạn nha!
>< :3 :))