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a)
204-84:12
=204-7
=197
b)
15.23+4.32-5.7
=15.8+4.9-5.7
=120+36-35
=156-35
=121
c)
56:53+23.22
=56-3+23+2
=53+25
=125+32
=157
d)
164.53+47.164
=(164.(53+47)
=164.100
=16400
tìm x:
219-7(x+1)=100
=>7(x+1)=219-100
=>7(x+1)=119
=>x+1=119:7
=>x+1=17
=>x=17-1
=>x=16
(3x-6).3=34
=>(3x-6).3=81
=>3x-6=81:3
=>3x-6=27
=>3x=27+6
=>3x=33
=>x=33:3
=>x=11
a)
204 - 84 : 12
= 204 - ( 84 : 12 )
= 204 - 7
= 107
b)
15 . 23 + 4 . 32 - 5 . 7
= 15 . 8 + 4 . 9 - 5 . 7
= 120 + 36 - 35
= 156 - 35
= 121
c)
56 : 53 + 23 . 22
= 5(6-3) + 2(3+2)
= 53 + 25
= 125 + 32
= 157
d) 164 . 53 + 47 . 164
= 164 . ( 53 + 47 )
= 164 . 100
= 16400
204-84:2=204-42=162
15.23+4.32-5.7=15.8+4.9-35=120+36-35=121
56:53+23.22=15625:125+8.4=125+32=157
164.53+47.164=164.(53+47)=164.100=16400
HỌC TỐT.
a) 204 - 84 : 12 = 204 - 7 = 197
b) 15.23 + 4 . 32 - 5.7 = 15 . 8 + 4 . 9 - 5 . 7 = 120 + 36 - 35 = 121
c) 56 : 53 + 23 . 22 = 15625 : 125 + 8 . 4 = 125 + 32 = 157
d) 164 . 53 + 47 x 164 = 164 x ( 53 + 47 ) = 164 x 100 = 16400
Bài 1:
a) A=1+22+24+.................+2100
2A=(1+22+24+.................+2100)
2A=2+23+...+2101
2A-A=(2+23+...+2101)-(1+22+24+.................+2100)
A=2101-1
b)bạn tự làm
c) C=-1/90-1/72-1/50-1/42-1/30-1/20-1/12-1/6-1/2
\(=-\left(\frac{1}{90}+\frac{1}{72}+...+\frac{1}{2}\right)\)
\(=-\left(\frac{1}{10.9}+\frac{1}{9.8}+...+\frac{1}{2.1}\right)\)
\(=-\left(\frac{1}{10}-\frac{1}{9}+\frac{1}{9}-\frac{1}{8}+...+\frac{1}{2}-1\right)\)
\(=-\left(\frac{1}{10}-1\right)\)
\(=-\left(-\frac{9}{10}\right)=\frac{9}{10}\)
Bài 2:
cứ tính lần lượt là ra
\(1a,204-84:12\)
\(=204-4=200\)
\(b,15.2^3+4.3^2-5.7\)
\(=15.8+4.9-35\)
\(=120+36-35=121\)
\(c,5^6:5^3+2^3.2^2\)
\(=5^3+2^5=125+32=157\)
\(d,164.54+164.47\)
\(=164\left(54+46\right)+164\)
\(=164.100+164=16400+164=16564\)
\(2,a,219-7\left(x+1\right)=100\)
\(\Rightarrow7\left(x+1\right)=219-100=119\)
\(\Rightarrow x+1=119:7=17\)
\(\Rightarrow x=17-1=16\)
\(b,\left(3x-6\right).3=3^4\)
\(\Rightarrow3x-6=3^4:3=3^3=27\)
\(\Rightarrow3x=27+6=33\)
\(\Rightarrow x=33:3=11\)