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Bài 1 :
36/1212 = 3/101
13/1313 = 1/101
3/101 + 1/101 = 4/101
Vậy 36/1212 + 13/1313 = 4/101.
Bài 2 :
A = 5/13 + 1/2 + -5/9 + -3/6 + 4/-9
A = 5/13 + 1/2 + -5/9 + -1/2 + -4/9
A = (1/2 + -1/2) + (-5/9 + -4/9) + 5/13
A = 0 + (-1) + 5/13
A = (-1) + 5/13 = -13/13 + 5/13 = 8/13.
Chúc bạn học giỏi nhé.
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3x + 7 ⋮ x + 2
3x + 6 + 1 ⋮ x + 2
3 ( x + 2 ) + 1 ⋮ x + 2
Vì 3 ( x + 2 ) ⋮ x + 2
=> 1 ⋮ x + 2
=> x + 2 thuộc Ư(1) = { 1; -1 }
=> x thuộc { -1; -3 }
Vậy........
\(\left(3x+7\right)⋮\left(x+2\right)\)
\(\Rightarrow\left(3x+6+1\right)⋮\left(x+2\right)\)
\(\Rightarrow1⋮\left(2+x\right)\)
\(\Rightarrow x+2\inƯ\left(1\right)=\left\{-1;1\right\}\)
\(\Rightarrow x\in\left\{-3;-1\right\}\)
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\(\frac{27^{20}+9^{20}}{9^{25}+81^5}=\frac{3^{60}+3^{60}}{3^{50}+3^{20}}=\frac{3^{20}\left(3^{40}+3^{40}\right)}{3^{20}\left(3^{30}+1\right)}=\frac{3^{40}.2}{3^{30}+1}\)
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x+5 chia hết x-2
(x+5) - (x-2) chia hết x-2
x+5 - x+2 chia hết x-2
7 chia hết x-2
x-2 thuộc Ư(7)={-1;1;-7;7}
x thuộc {1;3;-5;9}
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a. x + (x - 1) + (x - 2) + ... + (x - 50) = 255
=> x + x - 1 + x - 2 + ... + x - 50 = 255
=> 51.x - (1 + 2 + ... + 50) = 255
=> 51.x - (50 + 1).50:2 = 255
=> 51.x - 1275 = 255
=> 51.x = 255 + 1275
=> 51.x = 1530
=> x = 30
b. 3 + 6 + 9 + ... + x = 630
Số số hạng: (x - 3) : 3 + 1 = x /3 (số hạng)
=> (x + 3).(x/3):2 = 630
=> (x + 3).(x/3) = 1260
=> x.(x +3)/3 = 1260
=> x.(x + 3) = 3780
=> x.(x + 3) = 60.63
=> x.(x + 3) = 60.(60 + 3)
=> x = 60
c. 3.x - x + 1/2.x = 5\(\frac{1}{3}\)
=> x.(3 - 1 + 1/2) = 16/3
=> x.5/2 = 16/3
=> x = 16/3 : 5/2
=> x = 16/3 . 2/5
=> x = 32/15
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a)2 _<[x+3]_<3 =>x E{0} ;b)4_<[4-x]_<5=>x E {0} ; 1<[x+3] <5=>x {0;1}
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(x-2)^4=(x-2)^4.(x-2)^5
(x-2)^4:(x-2)^4=(x-2)^5
1=(x-2)^5
=>x-2=1=>x=1+2=3
x=9-5
x=4
k nhé
nên nhớ giá trị tuyệt đối nha