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Ta chia ra thành 2 hình như sau:
S HBCD là : 3 x 4 = 12 ( m2)
S AHEG là : 5 x 5 = 25 ( m2)
S bức tường cần sơn là : 12 + 25 = 37( m2)
Đ/s : 37 m2
a: x=77+50=127
b:x=80-49=31
c: x=50/450=1/9
d: =>159-25+x=43
=>x+134=43
=>x=-91
e: =>5(2x-1)=55
=>2x-1=11
=>2x=12
=>x=6
f: =>48:x=16
=>x=3
g: =>\(x\inƯC\left(36;40\right)\)
mà x<4
nên \(x\in\left\{1;2\right\}\)
h: =>\(x\inƯC\left(24;160\right)\)
mà x>2
nên \(x\in\left\{4;8\right\}\)
i: =>5^x*625=5^25
=>5^x=5^23
=>x=23
c)\(\left(1+\dfrac{1}{2}\right)\left(1+\dfrac{1}{3}\right)\left(1+\dfrac{1}{4}\right)....\left(1+\dfrac{1}{2020}\right)\left(1+\dfrac{1}{2021}\right)\)
\(=\left(\dfrac{1.2}{1.2}+\dfrac{1}{2}\right)\left(\dfrac{1.3}{1.3}+\dfrac{1}{3}\right)...\left(\dfrac{1.2021}{1.2021}+\dfrac{1}{2021}\right)\)
\(=\dfrac{3}{1.2}\cdot\dfrac{4}{1.3}\cdot\cdot\cdot\cdot\dfrac{2022}{1.2021}\)
\(=\dfrac{3.4.5...2022}{\left(1.1.1....1\right)\left(2.3.4...2021\right)}\)
\(=\)\(\dfrac{3.4.5...2022}{2.3.4...2021}\)
\(=\dfrac{2022}{2}=1011\)
\(d\))\(\left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)....\left(1-\dfrac{1}{199}\right)\left(1-\dfrac{1}{200}\right)\)
\(=\left(\dfrac{2}{1.2}-\dfrac{1}{1.2}\right)\left(\dfrac{3}{1.3}-\dfrac{1}{1.3}\right)....\left(\dfrac{200}{1.200}-\dfrac{1}{1.200}\right)\)
\(=\dfrac{1.2.3....199}{\left(1.1.1....1\right).\left(2.3.4....200\right)}\)
\(=\dfrac{1.2.3...199}{2.3.4...200}\)
Nếu mik làm sai mong bạn thông cảm
428=22.107
422=2.211
115=5.23
180=22.32.5
160=25.5
190=2.5.9
250=2.53
350=2.52.7
324=22.34
364=22.7.13
270=2.33.5
290=2.5.29
120=23.3.5
150=2.3.52
160=25.5
\(428=2^2\cdot107\)
\(422=2\cdot211\)
\(115=5\cdot23\)
\(180=2^2\cdot3^2\cdot5\)
\(160=2^5\cdot5\)
\(190=2\cdot5\cdot19\)
\(250=2\cdot5^3\)
\(350=2\cdot5^2\cdot7\)
\(324=2^2\cdot3^4\)
\(364=2^2\cdot7\cdot13\)
\(270=3^3\cdot2\cdot5\)
\(290=2\cdot5\cdot29\)
\(120=2^3\cdot3\cdot5\)
\(150=5^2\cdot2\cdot3\)
\(160=2^5\cdot5\)
-4/1 - (-4)/2 + (-4)/2 - (-4)/3 + .... + (-4)/97 - (-4)/98 + (-4)/98 - (-4)/99
= -4/1 - (-4)/99
= -4/1 + 4/99
= -392/99
Cảm ơn bn nhé