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\(\left[\left(6\times x-72\right):2-84\right]\times28=5628\)
\(\left(6\times x-72\right):2-84=5628:28\)
\(\left(6.x-72\right):2-84=201\)
\(\left(6.x-72\right):2=201+84\)
\(\left(6.x-72\right):2=285\)
\(6.x-72=285.2\)
\(6.x-72=570\)
\(6.x=570+72\)
\(6.x=642\)
\(x=642:6\)
\(x=107\)
[(6xX-72):2-84]x28=5628
⇒ (6xX-72):2-84=5629:28=201
⇒ (6xX-72):2=201+84=285
⇒ 6xX-72=285x2=570
⇒ 6xX=570+72=642
⇒ X= 642:6=107
⇒ X=107
![](https://rs.olm.vn/images/avt/0.png?1311)
[ ( 6 x - 72 ) : 2 - 84 ] . 28 = 5628
[ ( 6 x - 72 ) : 2 - 84 ] = 5628 : 28
[ ( 6 x - 72 ) : 2 - 84 ] = 201
[ ( 6 x - 49 ) : 2 - 84 ] = 201
[ ( 6 x - 49 ) - 84 ] = 201 . 2
[ ( 6 x - 49 ) - 84 ] = 402
( 6 x - 49 ) = 402 + 84
( 6 x - 49 ) = 486
6 x = 486 + 49
6 x = 535
x = 535 : 6
x = 84
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Tính nhanh :
a)8 x 45 + 55 x 8
= 8x(45+55)
= 8x100
=800
28 x 69 + 31 x 28
= 28x(69+31)
= 28x100
=2800
Ta có :
8 x 45 + 55 x 8
= 8 x ( 45 + 55 )
= 8 x 100
= 800
28 x 69 + 31 x 28
= 28 x ( 69 + 31 )
= 28 x 100
= 2800
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,\left(2x-16\right)^7=128\\ \Rightarrow\left(2x-16\right)^7=2^7\\ \Rightarrow2x-16=2\\ \Rightarrow2x=18\\ \Rightarrow x=9\\ b,x^3.x^2=2^8:2^3\\ \Rightarrow x^5=2^5\\ \Rightarrow x=5\\ c,3^{x-3}-3^2=2.3^2\\ \Rightarrow3^{x-3}-9=18\\ \Rightarrow3^{x-3}=27\\ \Rightarrow3^{x-3}=3^3\\ \Rightarrow x-3=3\\ \Rightarrow x=6\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a)\)
\(B(25) = \) \(\left\{0;1;25;50;...\right\}\)
\(Ư\left(28\right)=\left\{1;2;4;7;14;28\right\}\)
\(b)\)
\(x\in\left\{8;16\right\}\)
\(c)\)
\(60=2^2.3.5\)
\(84 = 2^2 . 3 . 7\)
28 x 16 + 28 x 84
= 28 x (16 + 84)
= 28 x 100
= 2800
bnTomoyo_Yaido làm đùnnhưng lần sau nên dùng dấu \(\Rightarrow\)