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a) $34-29+(-14)+129-(-114)$
$=34-29-14+129+114$
$=34+(129-29)+(114-14)$
$=34+100+100$
$=234$
b) $27\cdot(-35)+(-27)\cdot64-27$
$=(-27)\cdot35+(-27)\cdot64+(-27)\cdot1$
$=(-27)\cdot(35+64+1)$
$=(-27)\cdot(99+1)$
$=(-27)\cdot100$
$=-2700$
c) $160-(4\cdot5^2-3\cdot2^3)\cdot2-(-12)$
$=160-(4\cdot25-3\cdot8)\cdot2+12$
$=160-(100-24)\cdot2+12$
$=160-76\cdot2+12$
$=160-152+12$
$=160-(152-12)$
$=160-140$
$=20$
a, 34 - 29 + (-14) + 129 - (-114)
= 34 + (129 - 29) + (114 - 14)
= 34 + 100 + 100
= 234
b, 27.(-35) + (-27).64 - 27
= (-27).(35 + 64 + 1)
= - 27 . 100
= - 2700
c, 160 - (4.52 - 3.23).2 - (-12)
= 160 - (4.25 - 3.8).2 + 12
= 160 - (100 - 24).2 + 12
= 160 - 76.2 + 12
= 160 - 152 + 12
= 8 + 12
= 20
a) \(35\left(14-101\right)-14\left(35-10\right)\)
\(=35\cdot14-35\cdot101-14\cdot35+14\cdot10\)
\(=140-3535=-3395\)
b) \(5^2\cdot\left(-3\right)^3=25\cdot\left(-27\right)=-675\)
Bài 6:
a)\(\left(-18\right)-\left(-3\right)-12\)
\(=\left(-18\right)+3-12\)
\(=-15-12\)
\(=-27\)
b)\(85.\left(35-27\right)-35.\left(85-27\right)\)
\(=85.35-85.27-35.85+35.27\)
\(=85.\left(35-27-35\right)+35.27\)
\(=85.\left(-27\right)+35.27\)
\(=27.\left(-85+35\right)\)
\(=27.\left(-50\right)\)
\(=-1350\)
c)\(\left(-45\right).69+31.\left(-45\right)\)
\(=\left(-45\right).\left(69+31\right)\)
\(=\left(-45\right).100\)
\(=-4500\)
Bài 7:
a)\(\left(2-x\right)+10=-14\)
\(\Rightarrow2-x=-24\)
\(\Rightarrow x=26\)
b)\(14.\left|x\right|=28\)
\(\Rightarrow\left|x\right|=2\)
\(\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)
c)\(31-\left(17+x\right)=55\)
\(\Rightarrow17+x=-24\)
\(\Rightarrow x=-41\)
a) − 1 10 + 3 5 + − 1 2 = − 1 10 + 6 10 + − 5 10 = 0
b)
3 8 + − 3 4 + 7 12 : 5 6 + 1 2 = 9 24 + − 18 24 + 14 24 : 5 6 + 1 2 = 5 24 ⋅ 6 5 + 1 2 = 1 4 + 1 2 = 3 4
c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)
\(=\dfrac{3}{5}+\dfrac{2}{5}+\dfrac{-1}{4}+\dfrac{-7}{4}\)
\(=1-2=-1\)
Giải:
a)-1/12+4/3=-1/12+16/12=15/12=5/4
b)(-4/14-3/15)-(1/5-20/35-(-1)).7
=-17/35-22/35.7
=-17/35-22/5
=-171/35
c)3/5+-5/20+30/75+-7/4
=3/5+-1/4+2/5+-7/4
=(3/5+2/5)+(-1/4+-7/4)
=1+-2
=-1
d)5/6.-12/14+7/13
=-5/7+7/13
=-16/91
e)2/-9-5/-36-1/4
=-1/12-1/4
=-1/3
f)2/23+-5/12+7/18+21/23+-7/12
=(2/23+21/23)+(-5/12+-7/12)+7/18
=1+-1+7/18
=7/18
17.85+15.17-120
= 17(85+15)-120
=17.100-120
=1700-120
=1580
A = 12:{ 390 :[500-(125+35.7)]}
A=12:{ 390 :[500-(125+245)]}
A=12:{ 390 :[500-370]}
A=12:{ 390 :130}
A=12:3
A=4
75 - (3.52-4.23)
= 75 - ( 75 - 32)
= 75 - 43
= 32
B = 10+12+14+...+96+98
Tổng trên có số số hạng là:
(98-10):2+1=45 ( số )
\(\Rightarrow\text{B = 10+12+14+...+96+98}=\frac{\left(98+10\right).45}{2}=2430\)
17 . 85 + 15.17 - 120
= 17 ( 85 + 15 ) - 120
= 17 . 100 - 120
= 1700 - 120 = 1580
A = 12 : { 390 : [ 500 - ( 125 + 35 . 7 )]}
A = 12 : { 390 : [ 500 - ( 125 + 245 )]}
A = 12 : { 390 : [ 500 - 370 ]}
A = 12 : { 390 : 130 }
A = 12 : 3 = 4
75 - ( 3 . 52 - 4. 23 )
= 75 - ( 3 . 25 - 4 . 8 )
= 75 - ( 75 - 32 )
= 75 - 75 + 32
= 0 + 32 = 32
B = 10 + 12 + ... + 96 + 98
B có số số hạng là :
( 98 - 10 ) : 2 + 1 = 45 ( số )
B = ( 98 + 10 ) . 45 : 2 = 2430
a) \(17+188+183=205+183=388\)
b) \(80-\left[130-\left(12-4\right)^2\right]\)
\(=80-\left(130-64\right)\)
\(80-66=14\)
c) \(2^3.17-2^3.14\)
\(8.17-8.14\)
\(=8.\left(17-14\right)\)
\(=8.3=24\)
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