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Bài 1:
a) \(2^8.2.4=2^9.2^2=2^{11}\)
b) \(8^5:64=8^5:8^2=8^3\)
c) \(3^7:9=3^7:3^2=3^5\)
d) \(9^{17}.81=9^{17}.9^2=9^{19}\)
e) \(x^6.x.x^2=x^9\)
Bài 2:
a) \(2^x-15=17\)
\(\Rightarrow2^x=32\)
\(\Rightarrow2^x=2^5\)
\(\Rightarrow x=5\)
Vậy x = 5
b) \(2.3^x=162\)
\(3^x=162:2\)
\(3^x=81\)
\(\Rightarrow3^x=3^4\)
\(\Rightarrow x=4\)
Vậy x = 4
c) \(5.x.5^2=10\)
\(\Rightarrow x.5^3=10\)
\(\Rightarrow x.125=10\)
\(\Rightarrow x=10:125\)
\(\Rightarrow x=\frac{2}{25}\)
Vậy \(x=\frac{2}{25}\)
d) \(5.x^2-1=124\)
\(\Rightarrow5.x^2=125\)
\(\Rightarrow x^2=125:5\)
\(\Rightarrow x^2=5^2\)
\(\Rightarrow x=\pm5\)
Vậy \(x=\pm5\)
Câu 1:
a)28.2.4=28.2.22=211
b)85:64=85:82=83
c)37:9=37:32=35
d)917.81=917.92=919
e)x6.x.x2=x9
\(1,2^3.2^2.4^3=2^3.2^2.\left(2^2\right)^3=2^3.2^2.2^6=2^{3+2+6}=2^{11}\)
\(2,3^5.9^6.27^0=3^5.\left(3^2\right)^6.1=3^5.3^{12}=3^{5+12}=3^{17}\)
\(3,48.4^5.64^8\div3=48\div3.4^5.\left(4^3\right)^8=4^2.4^5.4^{24}=4^{2+5+24}=4^{31}\)
Câu 2:
b: \(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{n\left(n+1\right)}\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{n}-\dfrac{1}{n+1}\)
\(=1-\dfrac{1}{n+1}=\dfrac{n}{n+1}\)
c: \(\dfrac{1}{20}+\dfrac{1}{30}+...+\dfrac{1}{110}\)
\(=\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-...+\dfrac{1}{10}-\dfrac{1}{11}\)
\(=\dfrac{1}{4}-\dfrac{1}{11}=\dfrac{7}{44}\)
\(\left(20.2^4-12.2^3-48.2^2\right)^2:\left(-8\right)^3\)
\(=\left(20.16-12.9-48.4\right)^2:\left(-8\right)^3\)
\(=32^2:-512\)
\(=1024:-512=-2\)
\(\left(-2\right)\left(-3\right):\left(-1\right)-\left(-3\right)\left(-2\right):\left(-6\right)+\left(-2\right)\)
\(=-6-\left(-1\right)+\left(-2\right)\)
\(=-7\)
\(1.\left(-2\right)-\left(-3\right).\left(-4\right)-\left(-2\right).\left(-3\right)\)
\(=\left(-2\right)-12-6\)
\(=-20\)
Bài 1:
a) 12.18 + 14.3 - 255 : 17
= 216 + 42 - 15
= 258 - 15
= 243
b) 15.8 - (83 - 30 + 17) - 144 : 6
= 15.8 - (53 + 17) - 144 : 6
= 15.8 - 70 - 144 : 6
= 120 - 70 - 144 : 6
= 120 - 70 - 24
= 50 - 24
= 26
c) 24.(15 + 30 + 85 - 120) : 10
= 24.(45 + 85 - 120) : 10
= 24.(130 - 120) : 10
= 24.10 : 10
= 24.1
= 24
d) 15 - 25.8 : (100.2)
= 15 - 25.8 : 200
= 15 - 200 : 200
= 15 - 1
= 14
e) 32.5 - 22.7 + 1.5
= 9.5 - 4.7 + 1.5
= 45 - 28 + 5
= 17 + 5
= 22
g) (24.5 - 52.2) : (5.2) - 3
= (24.5 - 25.2) : (5.2) - 3
= (120 - 50) : 10 - 3
= 70 : 10 - 3
= 7 - 3
= 4
h) [(52.23 - 72.2) : 2].6 - 7.25
= [(25.8 - 49.2) : 2].6 - 7.32
= [(200 - 98) : 2].6 - 224
= [102 : 2].6 -224
= 51.6 - 224
= 306 - 224
= 82
i) 27 : 22 + 54 : 53.24 - 3.25
= 25 + 5.24 - 3.25
= 32 + 5.16 - 3.32
= 32 + 80 - 96
= 112 - 96
= 16
k) (37.35) : 310 + 5.24 - 73 : 7
= 312 : 310 + 5.24 - 72
= 32 + 5.24 - 72
= 9 + 5.16 - 49
= 9 + 80 - 49
= 89 - 49
= 40
Bài 2:
a) 547 + 389 + 453 + 211
= (547 + 453) + (389 + 211)
= 1000 + 600
= 1600
b) 125.98.2.8.25
= (125.8).(25.2.98)
= 1000.4900
= 4900000
c) 8466.15 + 170.4233
= 4233.2.15 + 170.4233
= 4233.30 + 170.4233
= 4233.(30 + 170)
= 4233. 200
= 846600
d) (62007 - 62006) : 62006
= 62007 : 62006 - 62006 : 62006
= 6 - 1
= 5
e) (112003 + 112002) : 112002
= 112003 : 112002 + 112002 : 112002
= 11 + 1
= 12
f) 4.24.52 - (33.18 + 33.12)
= 4.24.25 - [33.(18 + 12)]
= 4.25.24 - [27.30]
= 100.24 - 810
= 2400 - 810
= 1590
g) 23.7.53- (52.65 + 52.35)
= 8.7.125 - (25.65 + 25.35)
= 8.125.7 - [25.(65 + 35)]
= 1000.7 - [25.100]
= 7000 - 2500
= 4500
Xin lỗi nha, nhìu quá mk lm ko hết, thông cảm cho mk.
a: \(=105-96=9\)
b: =225+108=333
c: =-8x9-8x(-27)
\(=-8\left(9-27\right)=144\)
d: \(=1\cdot5+\left(-8\right)\cdot6-\left(-27\right)\cdot7=5-48+189=146\)
1.tìm x
(x-15): 5+22=24
(x-15): 5=24-22=2.
(x-15)=2.5=10.
x=10+15=25.
42 - ( 2x + 32 ) + 12 : 2 = 6
= 42 - (2x + 32 ) + 6 = 6.
42 - (2x + 32 ) = 6-6=0.
(2x+32) = 42 - 0 = 0.
2x = 0 - 32 = 0.
x = 0 : 2 = 0.
(x -105) :21 =15
(x-105) = 15.21=315.
x = 315 + 105 = 420.
x-105 :21=15
= x - 5 = 15.
x= 15 + 5 = 20.
( 2x -6 ) -(3x +7 )=0
...