- (- 85) - (40 - a) + 135
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a) a+38+(-42)+44
=a+38+[+(44-42)]
= a+38+2
= a+40
b) -(-85)-(40-a)+135
= 85-(40-a)+135
=(85+40)-135-a
=135-135-a
=0-a
k cho mình nha!
a) a+38+(-42)+44
=a+38-42+44
=a+44-42+38
=a+40
b) -(-85)-(40-a)+135
=85-40-a+135
=35-a+135
=35+135-a
=170-a
a: 785+135-85+65
=785-85+135+65
=700+200
=900
b: \(32\cdot39+52\cdot21-12\cdot39+21\cdot48\)
\(=39\cdot32-12\cdot39+52\cdot21+21\cdot48\)
\(=39\left(32-12\right)+21\left(52+48\right)\)
\(=39\cdot20+21\cdot100=2100+780=2880\)
c: \(5^4\cdot5^8:5^9\cdot6\cdot8\cdot7\)
\(=\dfrac{5^{12}}{5^9}\cdot48\cdot7\)
\(=125\cdot48\cdot7=42000\)
d: \(2021^0-\left\{15^2:\left[175+\left(2^3\cdot5^2-6\cdot25\right)\right]\right\}\)
\(=1-\dfrac{225}{175+8\cdot25-150}\)
\(=1-\dfrac{225}{25+220}\)
=1-1
=0
a) 785 + 135 - 85 + 65 = 900
b) 32.39 + 52.21 - 12.39 + 21.48 = 93.69
c) 5 mũ 4.5 mũ 8 ÷ 5 mũ 9.6 ÷ 8.7 = 0.134
d) 2021 mũ 0 - { 15 mũ 2 : [ 175 + ( 2 mũ 3.5 mũ 2 - 6.25 ) ] } = 2021 mũ 0 - { 152 : [ 175 + 17.27 ] } = 20210 - { 152 : 192.27 } = 20210 - 0.791 = 20209.209
a) \(\left(81+19\right)+35=135\)
b) \(\left(78+22\right)+\left(65+135\right)=100+200=300\)
c) \(\left(234+17716\right)+23=17950+23=17973\)
d) \(\left(99+1\right)+85=100+85=185\)
a = (81+19)+35
=100+35=135
b = (78+22)+(65+135)
=100+200=300
c = (234+17716)+23
=17950+23=17973
d = (99+1)+85
=100+85=185
a) 90 – ( 30 – 20) = 90 – 10
= 80
90 – 30 – 20 = 60 - 20
= 40
b) 100 – (60 + 10) = 100 – 70
= 30
100 - 60 + 10 = 40 + 10
= 50
c) 135 – (30 + 5) = 135 – 35
= 100
135 – 30 – 5 = 105 – 5
= 100
d) 70 + (40 – 10) = 70 + 30
= 100
70 + 40 – 10 = 110 -10
= 100
a) \(85^2+75^2+65^2+55^2-45^2-35^2-25^2-15^2\)
\(=\left(85^2-15^2\right)+\left(75^2-25^2\right)+\left(65^2-35^2\right)+\left(55^2-45^2\right)\)
\(=\left(85-15\right)\left(85+15\right)+\left(75-25\right)\left(75+25\right)+\left(65-35\right)\left(65+35\right)+\left(55-45\right)\left(55+45\right)\)
\(=70.100+50.100+30.100+10.100\)
\(=7000+5000+3000+1000\)
\(=16000\)
b) \(\frac{135^2+130.135+65^2}{135^2-65^2}\)
\(=\frac{135^2+2.60.135+65^2}{135^2-65^2}\)
\(=\frac{\left(135+65\right)^2}{\left(135-65\right)^2}\)
\(=\frac{200^2}{70^2}\) \(=\frac{200}{70}=\frac{20}{7}\)
Đây là một phép toán sai