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a, (231+69)*(28+72)
=300*100
=30000
c,đặt A=1+2+2^2+2^3+......+2^99+2^100
2A=2+2^2+2^3+2^4+......+2^100+2^101
2A-A=2^101-1
A=2^101-1/2
d,đặt S=5+5^3+5^5+.......+5^97+5^99
5^2S=5^3+5^5+5^7+.....+5^99+5^101
25S-S=5^101-5
24S=5^101-5
S=5^101-5/24
A) Ta có: 28 x ( 231 + 69) + 72 x ( 231 + 69)
= ( 28 + 72 ) x ( 231 + 69)
= 100 x 300
= 30 000
b) 2017 - { 52 x 22 - 11 [ 72 - 5 x 23 + 8 x (112 - 121) ] }
= 2017 - { 100 - 11 [ 49 - 40 + 8 x 0 ] }
= 2017 - { 100 - 1 [ 9 + 0 ]
= 2017 - { 100 - 1 x 9 }
= 2017 - { 99 x 9 }
= 2017 - 891
= 1126
c) 10 - { [ ( x : 3 + 17) : 10 + 2 x 24 ] : 10 } = 5
=> { [( x : 3 + 17 ) : 10 + 2 x 16 ] : 10 } = 10 - 5 = 5
=> [ ( x : 3 + 17) : 19 + 32 ] = 5 x 10 = 50
=> ( x : 3 + 17 ) : 19 = 50 - 32 = 18
=> x : 3 + 17 = 18 x 19 = 342
=> x : 3 = 342 - 17 = 325
=> x = 325 x 3
=> x = 975
Vậy x = 975
7: =6-7+4-3=0
8: =8x5-9x4+4x6=40-36+24=28
3: =231+26-209-26=22
a)56 : 52 + 2.22 - 122 b)75:72+46:43+ 225
c)38: 35 + 43 +124 d)85: 83 + 74:72+69
e)97: 95+ 3.32 - 1200. F)49: 47: 4.42 - 192
Bài làm :
a) \(5^6:5^2+2.2^2-12^2\)
\(=5^4+2^3-12^2\)
\(=625+8-144\)
\(=633-144\)
\(=489\)
b) \(7^5:7^2+4^6:4^3+225\)
\(=7^3+4^3+225\)
\(=343+64+225\)
\(=407+225\)
\(=632\)
c) \(3^8:3^5+4^3+124\)
\(=3^3+64+124\)
\(=27+64+124\)
\(=91+124\)
\(=215\)
d) \(8^5:8^3+7^4:7^2+69\)
\(=8^2+7^2+69\)
\(=64+49+69\)
\(=113+69\)
\(=182\)
e) \(9^7:9^5+3.3^2-120^0\)
\(=9^2+3^3-1\)
\(=81+27-1\)
\(=108-1\)
\(=107\)
f) \(4^9:4^7:4.4^2-192\)
\(=4^2:4^3-192\)
\(=4^{-1}-192\)
\(=-191,75\)