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-5 + (-37 - 45 + 51) - (-37 + 51)
= -5 - 37 - 45 + 51 + 37 - 51
= - (5 + 45) - (37 - 37) + (51 - 51)
= - 50 - 0 + 0
= - 50
- (15 - 47 + 58) + (15 - 47 ) + 3
= - 15 + 47 - 58 + 15 - 47 + 3
= (-15 + 15) + (47 - 47) - (58 - 3)
= 0 + 0 - 55
= - 55
(53 - 45 - 49) - (53 + 45 - 49)
= 53 - 45 - 49 - 53 - 45 + 49
= (53 - 53) + (-49 + 49) - (45 + 45)
= 0 + 0 - 90
= - 90
13 - 15 + 49 - 13 + 15 - 48
= (13 - 13) + (-15 + 15) + (49 - 48)
= 0 + 0 + 1
= 1
1, 42 x 53 + 47 x 156 - 47 x 114
= 42 x 53 + 47 x ( 156 - 114 )
= 42 x 53 + 47 x 42
= 42 x ( 53 + 47 )
= 42 x 100
= 4200
2, 53 x ( 51 + 4 ) + 53 x ( 49 + 96 ) + 53
= 53 x 51 + 53 x 4 + 53 x 49 + 53 x 96
= 53 x ( 51 + 49 ) + 53 x ( 96 + 4 ) + 53
= 53 x 100 + 53 x 100 + 53
= 5300 + 5300 + 53
= 10653
3, 42 x ( 15 + 96 ) + 6 x ( 25 + 4 ) x 7
= 42 x 15 + 42 x 96 + 42 x 25 + 42 x 4
= 42 x ( 15 + 25 ) + 42 x ( 96 + 4 )
= 42 x 40 + 42 x 100
= 42 x ( 100 + 40 )
= 42 x 140
= 5880
Tk mk nha !! ~
42. 53 + 47. 156 - 47. 114 = 42.53 +47.(156-114)
=42.53 +47. 42
= 42(53+47)
= 42.100 = 4200
53. ( 51 + 4 ) + 53. ( 49 + 96 ) + 53 = 53(51+4+49+96+1)
= 53. 201 = 10653
42. ( 15 + 96 ) + 6. ( 25 +4 ). 7 = 42. ( 15 + 96 ) + 42(25+4)
= 42(15+96+25+4)
= 42. 140 = 5880
mk lm xong rồi add friend nha
a) số các số: (65-2) : 3 +1=22
tổng: (65+2) x 22 : 2= 737
b, c , d làm tương tự nhé
1, \(\dfrac{x-1}{2009}+\dfrac{x-2}{2008}=\dfrac{x-3}{2007}+\dfrac{x-4}{2006}\)
\(\Leftrightarrow\left(\dfrac{x-1}{2009}-1\right)+\left(\dfrac{x-2}{2008}-1\right)=\left(\dfrac{x-3}{2007}-1\right)+\left(\dfrac{x-4}{2006}-1\right)\) ( Trừ mỗi vế cho 2 ta được phương trình như này nhé ! )
\(\Leftrightarrow\dfrac{x-2010}{2009}+\dfrac{x-2010}{2008}=\dfrac{x-2010}{2007}+\dfrac{x-2010}{2006}\)
\(\Leftrightarrow\dfrac{x-2010}{2009}+\dfrac{x-2010}{2008}-\dfrac{x-2010}{2007}-\dfrac{x-2010}{2006}=0\)
\(\Leftrightarrow\left(x-2010\right)\left(\dfrac{1}{2009}+\dfrac{1}{2008}-\dfrac{1}{2007}-\dfrac{1}{2006}\right)=0\)
Do \(\dfrac{1}{2009}+\dfrac{1}{2008}-\dfrac{1}{2007}-\dfrac{1}{2006}\ne0\) nên \(x-2010=0\Leftrightarrow x=2010\)
2, \(\dfrac{59-x}{41}+\dfrac{57-x}{43}+\dfrac{55-x}{45}+\dfrac{53-x}{47}+\dfrac{51-x}{49}=-5\)
\(\left(\dfrac{59-x}{41}+1\right)+\left(\dfrac{57-x}{43}+1\right)+\left(\dfrac{55-x}{45}+1\right)+\left(\dfrac{53-x}{47}+1\right)+\left(\dfrac{51-x}{49}+1\right)=0\)
\(\Leftrightarrow\dfrac{100-x}{41}+\dfrac{100-x}{43}+\dfrac{100-x}{45}+\dfrac{100-x}{47}+\dfrac{100-x}{49}=0\) \(\Leftrightarrow\left(100-x\right)\left(\dfrac{1}{41}+\dfrac{1}{43}+\dfrac{1}{45}+\dfrac{1}{47}+\dfrac{1}{49}\right)=0\) Do \(\dfrac{1}{41}+\dfrac{1}{43}+\dfrac{1}{45}+\dfrac{1}{47}+\dfrac{1}{49}\ne0\) nên \(100-x=0\Leftrightarrow x=100\)
\(53.\left(51+4\right)+53.\left(49+91\right)+53\\ =53.55+53.140+53.1\\ =53.\left(55+140+1\right)\\ =53.196\\ =10388.\)
\(53\cdot\left(51+4\right)+\left(49+91\right)+53\)
\(=53\cdot55+53\cdot140+53\cdot1\)
\(=53\cdot\left(55+140+1\right)\)
\(=53\cdot196\)
\(=53\cdot\left(200-4\right)\)
\(=53\cdot200+53\cdot4\)
\(=10600-212\)
\(=10388\)