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28 tháng 7 2017

\(a)47-\left[\left(45.2^4-5^2.12\right):14\right]\)

\(=47-\left[\left(45.16-25.12\right):14\right]\)

\(=47-\left[\left(720-300\right):14\right]\)

\(=47-\left[420:14\right]\)

\(=47-30\)

\(=17\)

\(b)50-\left[\left(20-2^3\right):2+34\right]\)

\(=50-\left[\left(20-8\right)\right]:2+34\)

\(=50-\left[12:2+34\right]\)

\(=50-\left[6+34\right]\)

\(=50-40\)

\(=10\)

\(c)10^2-\left[60:\left(5^6:5^4-3,5\right)\right]\)

\(=10^2-\left[60:\left(5^2-3,5\right)\right]\)

\(=10^2-\left[60:\left(25-3,5\right)\right]\)

\(=10^2-\left[60:21,5\right]\)

\(=100-\dfrac{120}{43}\)

\(=\dfrac{4180}{43}\)

\(d)50-\left[\left(50-2^3.5\right):2+3\right]\)

\(=50-\left[\left(50-8.5\right):2+3\right]\)

\(=50-\left[\left(50-40\right):2+3\right]\)

\(=50-\left[10:2+3\right]\)

\(=50-5+3\)

\(=50-8\)

\(=42\)

\(e)10-\left[\left(8^2-48\right).5+\left(2^3.10+8\right)\right]:28\)

\(=10-\left[\left(64-48\right).5+\left(8.10+8\right)\right]:28\)

\(=10-\left[16.5+\left(80+8\right)\right]:28\)

\(=10-\left[80+88\right]:28\)

\(=10-168:28\)

\(=10-6\)

\(=4\)

\(f)8697-\left[3^7:3^5+2.\left(13-3\right)\right]\)

\(=8697-\left[3^2+2.\left(13-3\right)\right]\)

\(=8697-\left[9+2.10\right]\)

\(=8697-9+20\)

\(=8697-29\)

\(=8668\)

\(g)2011+5\left[300-\left(17-7\right)^2\right]\)

\(=2011+5.\left[300-10^2\right]\)

\(=2011+5.\left[300-100\right]\)

\(=2011+5.200\)

\(=2011+1000\)

\(=3011\)

\(h)695-\left[200+\left(11-1\right)^2\right]\)

\(=695-\left[200+10^2\right]\)

\(=695-200+100\)

\(=695-300\)

\(=395\)

\(i)129-5\left[29-\left(6-1\right)^2\right]\)

\(=129-5\left[29-5^2\right]\)

\(=129-5\left[29-25\right]\)

\(=129-5.4\)

\(=129-20\)

\(=109\)

28 tháng 7 2017

help me

10 tháng 11 2017

a) 47 - [(45.16 - 25.12 ) : 14]

    = 47 - [ (720 - 300 ) : 14

    = 47 - [ 420 : 14 ]

    = 47 - 30 

    = 17

b) 50 - [ (20 - 8 ) : 2 + 34 ]

    = 50 - [ 12 : 2 + 34 ]

    = 50 - [ 6 + 34 ]

    = 50 - 40

    = 10

c) 100 - [ 60 : ( 15625 : 625 - 15 )

    = 100 - [ 60 : ( 25 - 15 ) ]

    = 100 - [ 60 : 10 ]

    = 100 - 6

    = 94

d)50-[(50-235)/2+3

=50-(10/2+3)

=50-8

=42

minh chi giupban duoc den do thoi ha

2 tháng 9 2016

\(\left[\left(6x-72\right):2-84\right].28=5628\)

\(\Rightarrow\left[\left(6x-72\right):2-84\right]=201\)

\(\Rightarrow\left[\left(6x-72\right):2\right]=285\)

\(\Rightarrow6x-72=570\)

\(\Rightarrow6x=642\)

\(\Rightarrow x=107\)

 

2 tháng 9 2016

\(A=2+2^2+2^3+2^4+...+2^{10}\)

\(A=\left(2+2^2\right)\left(2^3+2^4\right)+...+\left(2^9+2^{10}\right)\)

\(A=3.2+3.2^3+3.2^5+...+3.2^9\)

\(A=3\left(2+2^3+2^5+...+2^9\right)⋮3\)

Vậy A chia hết cho 3