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a) 128-3(x+4)=23
3(x+4)=128-23
3(x+4)=105
x+4=105:3
x+4=35
x=35-4
x=31
b) [(4x+28).3+55]:5=35
(4x+28).3+55=35.5
(4x+28).3+55=175
(4x+28).3=175-55
(4x+28).3=120
4x+28=120:3
4x+28=40
4x=40+28
4x=68
x=68:4
x=17
c) ( 12x - 43 ) . 83 = 4 . 84
12x-64=4.(84:83)
12x-64=4.8
12x-64=32
12x=32+64
12x=96
x=96:12
x=8
d) 720 : [ 4 - ( 2x - 5 ) ] = 23 . 5
720:[4-(2x-5)] = 8.5
720:[4-(2x-5)]=40
4-(2x-5)=720:40
4-(2x-5)=18
2x-5=4-18
2x-5=-14
2x=-14+5
2x=-9
x=-9:2
x=\(\frac{-9}{2}\)
Bài 1 :
a) \(\left(2^{17}+17^2\right).\left(9^{15}-3^{15}\right).\left(2^4-4^2\right)\)
\(=\left(2^{17}+17^2\right).\left(9^{15}-3^{15}\right).\left(16-16\right)\)
\(=\left(2^{17}+17^2\right).\left(9^{15}-3^{15}\right).0\)
\(=0\)
câu b sai đề rồi bạn , mình sủa lại đề nha :
b) \(\left(8^{2017}-8^{2015}\right)\div\left(8^{2014}.8\right)\)
\(=\left(8^{2017}-8^{2015}\right)\div8^{2015}\)
\(=8^{2017}\div8^{2015}-8^{2015}\div8^{2015}\)
\(=8^2-1\)
\(=64-1\)
\(=63\)
c) \(\left(1^3+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left(3^8-81^2\right)\)
\(=\left(1^3+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left[3^8.\left(3^4\right)^2\right]\)
\(=\left(1^3+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left[3^8-3^8\right]\)
\(=\left(1^3+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).0\)
\(=0\)
d) \(\left(2^8+8^3\right)\div\left(2^5.2^3\right)\)
\(=\left[2^8+\left(2^3\right)^3\right]\div2^8\)
\(=\left[2^8+2^9\right]\div2^8\)
\(=2^8\div2^8+2^9\div2^8\)
\(=1+2\)
\(=3\)
Bài 2 :
a) \(125^5\div25^3=\left(5^3\right)^5\div\left(5^2\right)^3=5^{15}\div5^6=5^9\)
b) \(27^6\div9^3=\left(3^3\right)^6\div\left(3^2\right)^3=3^{18}\div3^6=3^{12}\)
c) \(4^{20}\div2^{15}=\left(2^2\right)^{20}\div2^{15}=2^{40}\div2^{15}=2^{25}\)
d) \(24^n\div2^{2n}=24^n\div4^n=6^n\)
A, (-25). 21. (-2)2. (-|-3|). (-1)2015
B, (-5)3. 67. (-|-2|). (-1)2014
C, 35.18 – 5.7.28 + 35. (-90)
D, 24. (16 – 5) – 16. (24 – 5)
E, - 79. (73 – 27) – 73. (-79 + 27)
G, 31. (-18) + 31. (-8)-31
M, -48 + 48. (-78) + 48. (-21)
N, -|-17| + 2. [ 24: (-8) + (-5)2]
I, -|-7|. [(-2)4 + (-36): (-32)] – (-5)3
\(a,[\left(8.x-12\right):4].3^3.3=3^6.6\)
\(\left(8x-12\right):4=54\)
\(8x-12=216\)
\(8x=228\)
\(x=28,5\)
\(b,41-2^{x+1}=9\)
\(2^{x+1}=41-9\)
\(2^{x+1}=32\)
\(2^{x+1}=2^5\)
\(\Rightarrow x+1=5\)
\(\Rightarrow x=4\)
\(16+\left(-6\right)+\left(-8\right)+7\)\(=16-6-8+7\)\(=\left(16-6\right)-\left(8-7\right)\)\(=10-1=9\)
\(\left(-8\right)-[\left(2015^0\right)-14+7]\)\(=-8-\left(1-14+7\right)\)\(=-8-\left(-6\right)=-2\)
\(\left(-31\right)-[82-\left(-17\right)]\)\(=-31-\left(82+17\right)\)\(=-31-99=-130\)
\(6\left(-2\right)^3+5\left(-4\right)-\left(-12\right)\)\(=6\left(-8\right)+\left(-20\right)+12\)\(=-48-20+12=-56\)
a. 3 . 62 . 8 + 2 .17 . 12 + 4 . 6 . 21
= 186 . 8 + 34 . 12 + 24 . 21
= 1488 + 408 + 504
= 1896 + 504
=2400
a)-50.(-8)
=400
b) 16.125-(1+8):9
=20750-9:9
=20750-1
=20150
ti-ck nha
a) ( -67 + 17 ) . ( -8 )
= (-50) . (-8)
= 400
b) 42 . 53 - ( 20150 + 8) : 32
= 16 . 125 - (1 + 8) : 9
= 2000 - 9 : 9
= 2000 - 1
Học tốt!