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a) \(\dfrac{2^4\cdot5^2\cdot7}{2^3\cdot5\cdot7^2\cdot11}=\dfrac{2^3\cdot5\cdot10\cdot7}{2^3\cdot5\cdot7\cdot77}=\dfrac{10}{77}\)
\(\dfrac{2^3\cdot3^3\cdot5^3\cdot7\cdot8}{3\cdot2^4\cdot5^3\cdot14}=\dfrac{2^3\cdot3\cdot5^3\cdot7\cdot3^2\cdot8}{3\cdot2^3\cdot2\cdot5^3\cdot14}=\dfrac{7\cdot3^2\cdot8}{2\cdot14}=\dfrac{63\cdot8}{2\cdot14}=18=\dfrac{1386}{77}\)
\(80-\left(4.5^2-3.2^3\right)=2^{10}-\left(x-4\right)\\ 80-\left(4.25-3.8\right)=1024-\left(x-4\right)\\ 80-\left(100-24\right)=1024-\left(x-4\right)\\ 80-76=1024-\left(x-4\right)\\ 4=1024-\left(x-4\right)\\ x-4=1024-4\\ x-4=1024-4\\ x-4=1020\\ x=1020+4\\ x=1024\)
80-(4.52-3.23)=210-(x-4)
80-(4.25-3.8)=1024-(x-4)
80-(100-24)=1024-(x-4)
80-76=1024-(x-4)
4=1024-(x-4)
4-1024= x-4
1020= x-4
1020+4=x
1024=x
\(3^0.3^5.3^7=3^{12}\)
\(16^3:4^2=4^6:4^2=4^4\)
\(2^4.4^3=2^4.2^6=2^{10}\)
\(2^4.5^4\left(2.5\right)^4=10^4\)
S = 1 + 2 + 2² + 2³ + 2⁴ + ... + 2¹⁰⁰
2S = 2 + 2² + 2³ + 2⁴ + ... + 2¹⁰¹
S = 2S - S
= (2 + 2² + 2³ + ... + 2¹⁰¹) - (1 + 2 + 2² + ... + 2¹⁰⁰)
= 2¹⁰¹ - 1
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S = 1.2 + 2.3 + 3.4 + ... + 99.100 + 100.101
3S = 1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2) + ... + 99.100.(101 - 98) + 100.101.(102 - 99)
= 1.2.3 - 1.2.3 + 2
3.4 - 2.3.4 + 3.4.5 - ... - 98.99.100 + 99.100.101 - 99.100.101 + 100.101.102
= 100.101.102
S = 100 . 101 . 102 : 3
= 343400
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Q = 1² + 2² + 3² + ... + 100² + 101²
= 101.102.(2.101 + 1) : 6
= 348551
26 và 82
Ta có : 26= 23.2= ( 23 )2 = 82
Mà 82=82 => 26 = 82
Vậy 26 = 82
\(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}=\frac{1}{5}\)
\(\frac{1^2}{1.2}.\frac{2^2}{2.3}.\frac{3^2}{3.4}.\frac{4^2}{4.5}=\frac{1^2.2^2.3^2.4^2}{1.2^2.3^2.4^2.5}=\frac{1}{5}\)
c) {[(20 - 2.3).5] - 2.5} : 2 + (4.5)²
= {(20 - 6).5] - 10} : 2 + 20²
= (14.5 - 10) : 2 + 400
= (70 - 10) : 2 + 400
= 60 : 2 + 400
= 30 + 400
= 430
d) (1² + 2² + 3² + ... + 100²) . (2⁴ - 4²)
= (1² + 2² + 3² + ... + 100²) . (16 - 16)
= (1² + 2² + 3² + ... + 100²) . 0
= 0
Bài 2
a) -2x < 5
2x > 5
x > 5/2
b) [31 - (x + 5)].11 = 121
31 - (x + 5) = 121 : 11
31 - (x + 5) = 11
x + 5 = 31 - 11
x + 5 = 20
x = 20 - 5
x = 15
c) (x + 1)³ = 27
(x + 1)³ = 3³
x + 1 = 3
x = 3 - 1
x = 2
4.5^2 - 3^2 : 2^4
= 4. 25 - 9 : 16
= 100 - 9 : 16
= 100 - 0,5625
= 99,4375
\(4.5^2-3^2:2^4\)
\(=4.25-9:16\)
\(=100-0,5625\)
\(=99,4375\)