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bài 1 : a) 2x-18=2^3*3^2
2x-18=8*9
2x-18=72
2x=72+18
2x=90
x=90:2
x=45
tick đi mình làm tiếp cho
a)
2x-18=2^3.3^2
<=>2x-18=72
<=>2x=90
<=>x=45
b)
2154-(3x-129)=9^7.9^15:9^20+1827
<=>2154-3x+129=9^2+1927
<=>2283-3x=1908
<=>3x=375
<=>x=125
a
24-42=0
=>(217 + 172).(915 - 315).(24 - 42)=0
b
(71997 - 71995) : (71994.7)
=71995(72-1):71995=48
c) (12 + 23 + 34 + 45).(13+ 23 + 33 + 43).(38 - 812)
=(12 + 23 + 34 + 45).(13+ 23 + 33 + 43).0=0
d) (28 + 83) : (25.23)
=(28+29);28=3
(23.94+93.45):(92.10-92)
= ( 8. 94+93.9.5):(81.10-81)
= (8.94+94.5):(810-81)
=[94.(8+5)]:729
=[94.13]:729
=6561.13:729
=6561:729.13
=9.13
=117
Mk nhanh nhat day
(23.94+93.45):(92.10-92)
=(23.94+5.94):(81.10-81)
=[94.(8+5)]:(810-81)
=(6561.13):729
=85296:729
=117
a) 125 + 70 + 375 + 230 = (125 + 375) + (70 + 230) = 500 + 300 = 800
b) 62 : 4 . 3 + 2 . 52 = 62 : 22 . 3 + 2 . 25 = 32 . 3 + 50 = 33 + 50 = 27 + 50 = 77
c) 150 : [25 . (18 - 42)] = 150 : (25 . 2) = 150 : 50 = 3
\(b,\left(1^2+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left(3^8-81^2\right)\)
\(=\left(1^2+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left[3^8-\left(3^4\right)^2\right]\)
\(=\left(1^2+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left(3^8-3^8\right)\)
\(=\left(1^2+2^3+3^4+4^5\right)\left(1^3+2^3+3^3+4^3\right).0=0\)
a, = 71995 . ( 72 - 1) : 71995 = 49 - 1 = 48
b, = ........... x ( 38 - 38) = 0
a, 32 x 35 + 32 x 65 b, 150 : [ 25 x ( 18- 42)]
= 32 x ( 35 +65) = 150 : [ 25 x ( 18-16)]
= 9 x 100 = 150 : ( 25 x 2)
= 900 = 150 : 50 = 3
c, 57 : 54 - 21 x 22
= 53- 2 x 4
= 125-8
=117
a) 3 ^ 2 x 35 + 3 ^ 2 x 65 = 9 x 35 + 9 x 65 = 9 x ( 65 + 35 ) = 9 x 100 = 900
1. a) 17.85 + 15.17 - 120
= 17.( 85 + 15) - 120
= 17. 100 -120
= 1700 - 120
= 1580
b) 20 - [ 30 - (5 - 1)2 ]
= 20 - [ 30 - 42 ]
= 20 - [ 30 - 16 ]
= 20 - 14
= 6
2. a) 70 - 5.(x - 3) = 45
5.(x - 3) = 70 - 45
5.(x -3) = 25
x - 3 = 25 : 5
x - 3 = 5
x = 5 + 3
x = 8
b) 10 + 2.x = 45 : 43
10 + 2.x = 42
10 + 2.x = 16
2.x = 16 - 10
2.x = 6
x = 6 : 2
x =3
1)a:17.85+15.17-120=17.(85+15)-120=17.100-120=1700-120=1580
b: 20-[30-(5-1)^2 = 20-[30-4^2]=20-(30-16)=20-15=5
2)
a: 70-5(x-3)=45
5(x-3) = 70-45=25
x-3 = 25:5=5
x= 5+3=8
b: 10+2x = 4^5:4^3
10+2x = 4^2
10+2x = 16
2x = 16-10=6
x = 6:2=3
a) 2x : 22 = 3.23 + 23
2x-2 = 23.(3+1) = 23.4=23.22 = 25
=> x -2 = 5
x = 7
b) 65.59+65.42 - 13.5
= 65.(59+42) - 13.5
= 65.101 - 13.5
= 65.101- 65
= 65.(101-1) = 65.100 = 6500
45-[(18-15)2 + 24 ]
= 45 - (32 + 24) = 45 - 25 = 20