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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
a) \(\frac{{ - 3}}{7}.\frac{2}{5} + \frac{2}{5}.\left( { - \frac{5}{{14}}} \right) - \frac{{18}}{{35}}\)
\(\begin{array}{l} = \frac{2}{5}.\left( {\frac{{ - 3}}{7} + \frac{{ - 5}}{{14}}} \right) - \frac{{18}}{{35}}\\ = \frac{2}{5}.\left( {\frac{{ - 6}}{{14}} + \frac{{ - 5}}{{14}}} \right) - \frac{{18}}{{35}}\\ = \frac{2}{5}.\frac{{ - 11}}{{14}} - \frac{{18}}{{35}} = \frac{{ - 11}}{{35}} - \frac{{18}}{{35}} = \frac{{ -29}}{{35}}\end{array}\)
b) \(\left( {\frac{2}{3} - \frac{5}{{11}} + \frac{1}{4}} \right):\left( {1 + \frac{5}{{12}} - \frac{7}{{11}}} \right)\)
\(\begin{array}{l} = \left( {\frac{{2.11.4}}{{3.11.4}} - \frac{{5.3.4}}{{11.3.4}} + \frac{{1.3.11}}{{4.3.11}}} \right):\left( {\frac{11.12}{11.12} + \frac{{5.11}}{{12.11}} - \frac{{7.12}}{{11.12}}} \right)\\ = \left( {\frac{{88 - 60 + 33}}{{121}}} \right):\left( { \frac{{121+55 - 84}}{{121}}} \right)\\ = \frac{{61}}{{121}}:\frac{{92}}{{121}} = \frac{{61}}{{121}}.\frac{{121}}{{92}}= \frac{{61}}{{92}}\end{array}\)
c) \(\left( {13,6 - 37,8} \right).\left( { - 3,2} \right)\)
\( = \left( { - 24,2} \right).\left( { - 3,2} \right) = 77,44\)
d) \(\left( { - 25,4} \right).\left( {18,5 + 43,6 - 16,8} \right):12,7\)
\(\begin{array}{l} = \left( { - 25,4} \right).\left( {62,1 - 16,8} \right):12,7\\ = \left( { - 25,4} \right).45,3:12,7\\ = \left( { - 25,4} \right):12,7.45,3\\ = (- 2).45,3 = - 90,6\end{array}\)
a: \(=\dfrac{2}{5}\cdot\left(-\dfrac{3}{7}-\dfrac{5}{14}\right)-\dfrac{18}{35}\)
\(=\dfrac{2}{5}\cdot\dfrac{-6-5}{14}-\dfrac{18}{35}\)
\(=\dfrac{2}{5}\cdot\dfrac{-11}{14}-\dfrac{18}{35}=-\dfrac{22}{70}-\dfrac{18}{35}=\dfrac{-58}{70}=-\dfrac{29}{35}\)
b: \(=\dfrac{88-60+33}{132}:\dfrac{132+55-84}{132}\)
\(=\dfrac{61}{132}\cdot\dfrac{132}{103}=\dfrac{61}{103}\)
c: \(=-24.2\cdot\left(-3.2\right)=24.2\cdot3.2=77.44\)
d: \(=\dfrac{-25.4}{12.7}\cdot45.3=-2\cdot45.3=-90.6\)
1.
a) \(125+80+375+220\)
\(=\left(125+375\right)+\left(80+220\right)\)
\(=500+300\)
\(=800\)
b) \(25.11.8.4.125\)
\(=\left(25.4\right).\left(8.125\right).11\)
\(=100.1000.11\)
\(=1100000\)
c) \(18.74+18.27-18\)
\(=18.\left(74+27-1\right)\)
\(=18.100\)
\(=1800\)
d) \(75.23+75.77-500\)
\(=75.\left(23+77\right)-500\)
\(=75.100-500\)
\(=7500-500\)
\(=7000\)
e) \(150:\left[25.\left(18-4^2\right)\right]\)
\(=150:\left[25.\left(18-16\right)\right]\)
\(=150:\left[25.2\right]\)
\(=150:50\)
\(=3\)
f) \(125.23.2.8.50\)
\(=\left(125.8\right).\left(2.50\right).23\)
\(=1000.100.23\)
\(=2300000\)
g) \(235+88+165+12\)
\(=\left(235+165\right)+\left(88+12\right)\)
\(=400+100\)
\(=500\)
h) \(71.32+71.68-1100\)
\(=71.\left(32+68\right)-1100\)
\(=71.100-1100\)
\(=7100-1100\)
\(=6000\)
i) \(6^7:6^6+4^3.2-24^0\)
\(=6+64.2-1\)
\(=6+128-1\)
\(=133\)
j) \(546-6.\left[158:\left(30+7^2\right)\right]\)
\(=546-6.\left[158:\left(30+49\right)\right]\)
\(=546-6.\left[158:79\right]\)
\(=546-6.2\)
\(=546-12\)
\(=534\)
k) \(268+147+132+253\)
\(=\left(268+132\right)+\left(147+253\right)\)
\(=400+400\)
\(=800\)
2.
a) \(7x=707\)
\(x=707:7\)
\(x=101\)
b) \(6x+5=47\)
\(6x=47-5\)
\(6x=42\)
\(x=42:6\)
\(x=7\)
c) \(35:\left(x+1\right)=7\)
\(x+1=35:7\)
\(x+1=5\)
\(x=5-1\)
\(x=4\)
d) \(12+\left(29-3x\right)=35\)
\(29-3x=35-12\)
\(29-3x=23\)
\(3x=29-23\)
\(3x=6\)
\(x=6:3\)
\(x=2\)
e) \(2.4^x+10^1=138\)
\(2.4^x=138-10\)
\(2.4^x=128\)
\(4^x=128:2\)
\(4^x=64=4^3\)
\(\Rightarrow x=3\)
f) \(7x=140\)
\(x=140:7\)
\(x=20\)
g) \(7\left(15-x\right)+14=84\)
\(7\left(15-x\right)=84-14\)
\(7\left(15-x\right)=70\)
\(15-x=70:7\)
\(15-x=10\)
\(x=15-10\)
\(x=5\)
h) \(3^x.5-15=390\)
\(3^x.5=390+15\)
\(3^x.5=405\)
\(3^x=405:5\)
\(3^x=81=3^4\)
\(\Rightarrow x=4\)
a) 217 +[43 + (-217) + (-23)] = 217 + 43 + (-217) + (-23)
= 217 + (-217) + 43 + (-23) = [217 + (-217)] + [43 + (-23)]
= 0 + (43 - 23) = 20.
b) Tổng của tất cả các số nguyên có giả trị tuyệt đối nhỏ hơn 10 là 0.
1135/23-167/32+330/23
=(1135/23-330/23)+167/32
=805/23+167/32
=35+167/32
=1120/32+167/32
=1287/32
1. Tính tổng:
a) (-37) + 14 + 26 + 37 = 40
b) (-24) + 6 + 10 + 24 = 16
c) 15 + 23 + (-25) + (-23) = -10
d) 60 + 33 + (-50) + (-33) = 10
e) (-16) + (-209) + (-14) + 209 = -30
f) -32 + {-54 : [(-2)8 + 7] . (-2)2} = -32 + {-54 : [(-256) + 7] . 4} = -32 + {-54 : (-249) . 4} = -32 + {-54 : (-996)} = -32 + 0 = -32
2. Thực hiện phép tính:
a) (36 + 79) + (145 - 79 - 36) = 115 + 30 = 145
b) 10 - [12 - (-9 - 1)] = 10 - [12 - (-10)] = 10 - [12 + 10] = 10 - 22 = -12
c) (38 - 29 + 43) - (43 + 38) = 52 - 81 = -29
d) 271 - [(-43) + 271 - (-17)] = 271 - [-43 + 271 + 17] = 271 - [245] = 26
3. Tính hợp lý:
a) 31 . (-18) + 31 . (-81) - 31 = -558 + (-2511) - 31 = -3100
b) (-12) . 47 + (-12) . 52 + (-12) = -564 + (-624) + (-12) = -1200
c) 13 . (23 + 22) - 3 . (17 + 28) = 13 . 45 - 3 . 45 = 585 - 135 = 450
d) -48 + 48 . (-78) + 48 . (-21) = -48 + (-3744) + (-1008) = -4800
1. Tính tổng:
a) (-37) + 14 + 26 + 37 = 40
b) (-24) + 6 + 10 + 24 = 16
c) 15 + 23 + (-25) + (-23) = -10
d) 60 + 33 + (-50) + (-33) = 10
e) (-16) + (-209) + (-14) + 209 = -30
f) -32 + {-54 : [(-2)8 + 7] . (-2)2} = -32 + {-54 : [(-256) + 7] . 4} = -32 + {-54 : (-249) . 4} = -32 + {-54 : (-996)} = -32 + 0 = -32
2. Thực hiện phép tính:
a) (36 + 79) + (145 - 79 - 36) = 115 + 30 = 145
b) 10 - [12 - (-9 - 1)] = 10 - [12 - (-10)] = 10 - [12 + 10] = 10 - 22 = -12
c) (38 - 29 + 43) - (43 + 38) = 52 - 81 = -29
d) 271 - [(-43) + 271 - (-17)] = 271 - [-43 + 271 + 17] = 271 - [245] = 26
3. Tính hợp lý:
a) 31 . (-18) + 31 . (-81) - 31 = -558 + (-2511) - 31 = -3100
b) (-12) . 47 + (-12) . 52 + (-12) = -564 + (-624) + (-12) = -1200
c) 13 . (23 + 22) - 3 . (17 + 28) = 13 . 45 - 3 . 45 = 585 - 135 = 450
d) -48 + 48 . (-78) + 48 . (-21) = -48 + (-3744) + (-1008) = -4800
a) − 105 + − 25 + ( − 105 ) + 50
= 105 + 25 + ( - 105) + 50
= [105 + ( -105)] + ( 25 + 50 )
= 0 + 75 = 75
b) 465 + − 38 + − 465 − 12 − − 42
= 465 + ( - 38) + ( -465) – 12 – 42
= [ 465 + (- 465) ] – ( 12 + 42 )
= 0 – 54 = 0 + ( -54 ) = -54
c) 65. − 19 + − 19 .24 + − 19 .11
= ( - 19) . ( 65 + 24 + 11 )
= ( -19) . 100 = -1900
d) − 3 2 + 2 3 − − 5 2 + 4 3
= 9 + 8 – 25 + 64 = 56
d ) \(\left|-18\right|:\left(14-11^2\right)\)
\(=18:\left(14-121\right)\)
\(=18:-107\)
\(=-\frac{18}{107}\)
e ) \(\left(-25\right)+1945+\left(-75\right)+\left(-1945\right)\)
\(=\left[\left(-25\right)+\left(-75\right)\right]+\left[1945+\left(-1945\right)\right]\)
\(=-100+0\)
\(-100\)
f ) \(217+\left[43+\left(-217\right)+\left(-23\right)\right]\)
\(=217+43+\left(-217\right)+\left(-23\right)\)
\(=\left[217+\left(-217\right)\right]+\left[43+\left(-23\right)\right]\)
\(=0+20\)
\(=20\)
Chúc bạn học tốt !!!