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1) 3.52 - 16 : 22
= 3 . 25 - 24 : 22
= 75 - 22
= 75 - 4
= 71
2) 23 .17 -23 . 14
= 23 . ( 17 - 14 )
= 8 . 3
= 24
3) 17.85 + 15.17 - 120
= 17 . ( 85 + 17 ) - 120
= 75 . 102 - 120
= 7650 - 120
= 7530
4) 20 - [30-(5 - 1)2]
= 20 - ( 30 - 42 )
= 20 - ( 30 - 16 )
= 20 - 14
= 6
5) 36 . 32 + 23 .22
= 38 + 25
= 6561 + 32
= 6593
6) 17 .85 + 15.17 - 120 + 20120
= 17 . ( 85 + 15 ) - 120 + 1
= 17 . 100 - 120 + 1
= 1700 - 120 + 1
= 1580 + 1
= 1581
7) 37. 24 + 37. 76 + 63 . 79 + 21. 63
= 37 . ( 24 + 76 ) + 63 . ( 79 + 21 )
= 37 . 100 + 63 . 100
= 100 . ( 37 + 63 )
= 100 . 100
= 10000
1) \(3.5^2-16.2^2=3.25-16.4=75-64=11\)
2) \(2^3.17-2^3.14=2^3.\left(17-14\right)=8.3=24\)
3) \(17.85+15.17-120=17.\left(85+15\right)-120\)
\(=17.100-120=1700-120=1580\)
4)\(20-\left[30-\left(5-1\right)^2\right]=20-\left[30-4^2\right]\)
\(=20-\left[30-16\right]=20-14=6\)
5) \(3^6.3^2+2^3.2^2=3^8+2^5=6561+32=6593\)
6) \(17.85+15.17-120+2012^0=17.\left(85+15\right)-120+1\)
\(=17.100-119=1700-119=1581\)
7) \(37.24+37.76+63.79+21.63\) \(=37.\left(24+76\right)+63.\left(79+21\right)\)
\(=37.100+63.100=100.\left(37+63\right)=100.100=10000\)
Bài 2:a)<=>5(x+4) =125-38
<=>5(x+4)=87
<=>x+4=17,4
<=>x=17,4-4=13.4
b)<=> ( 3x – 24) . 73 = 2.74
<=> (3x – 16) = 2.74 : 73
<=> (3x – 16) =2.7
<=>3x – 16 = 14
<=> 3x = 30
<=> x = 10
c)=> xϵ ƯC (70, 84) và x > 8
Ta có: 70 = 2. 5. 7 => ƯCLN( 70,84) = 2. 7 = 14
84 = 22. 3. 7
=> ƯC (70, 84) = Ư(14) = { 1 ;2; 7; 14 }
Vì x > 8 => x = 14
d)=>xϵ BCNN (12, 25, 30) và 0 < x < 500
=>BC(12,25,30)=B(300) = { 0; 300; 600; …}
Vì 0 < x < 500
=> x = 300
giup minh nha cac ban . lam duoc minh se tick cho va ket ban . cam on cac ban
1, a,b ko chia hết cho 3 nhưng có cùng số dư khi chia cho 3
=> a,b cùng chia 3 dư 1 hoặc 2
sau đó xét 2 TH;
=> ab chia 3 dư 1 => ab-1 là bội của 3 (ĐPCM)
a, \(11^{25}\div11^{23}-3^5\div\left(1^{10}+2^3\right)-60\)
\(=11^{25}\div11^{23}-3^5\div\left(1+8\right)-60\)
\(=11^{25}\div11^{23}-3^5\div3^2-60\)
\(=11^2-3^3-60\)
\(=121-27-60\)
\(=94-60=34\)
b, \(2345-1000\div\left[19-2\left(21-18\right)^2\right]\)
\(=2345-1000\div\left[19-2.3^2\right]\)
\(=2345-1000\div\left[19-2.9\right]\)
\(=2345-1000\div1=2345-1000=1345\)
c, \(128-\left[68+8\left(37-35\right)^2\right]\div4\)
\(=128-\left[68+8.2^2\right]\div4\)
\(=128-\left[68+8.4\right]\div4\)
\(=128-\left[68+32\right]\div4\)
\(=128-100\div4=128-25=103\)
d, \(107-\left\{38+\left[7.3^2-24\div6+\left(9-7\right)^3\right]\right\}\div15\)
\(=107-\left\{38+\left[7.9-4+2^3\right]\right\}\div15\)
\(=107-\left\{38+\left[63-4+8\right]\right\}\div15\)
\(=107-\left\{38+\left[59+8\right]\right\}\div15\)
\(=107-\left\{38+67\right\}\div15\)
\(=107-105\div15\)
\(=107-7=100\)
e, \(50-\left[50-\left(2^3.5\right)\div2+3\right]\)
\(=50-\left[50-8.5\div2+3\right]\)
\(=50-\left[50-40\div2+3\right]\)
\(=50-\left[50-20+3\right]\)
\(=50-\left[30+3\right]\)
\(=50-33=17\)
Bài 2 :
a, \(5\left(x-9\right)=350-5^2\)
\(5\left(x-9\right)=350-25\)
\(5\left(x-9\right)=325\)
\(x-9=325\div5\)
\(x-9=65\)
\(\Rightarrow x=65+9\)
\(\Rightarrow x=74\)
Vậy x = 74
b, \(2\left(x-51\right)=2.2^3+20\)
\(2\left(x-51\right)=16+20\)
\(2\left(x-51\right)=36\)
\(x-51=36\div2\)
\(x-51=18\)
\(\Rightarrow x=18+51\)
\(\Rightarrow x=69\)
Vậy x = 69
c, \(2.3^x=162\)
\(\Rightarrow2.3^x=2.3^4\)
\(\Rightarrow3^x=3^4\)
\(\Rightarrow x=4\)
Vậy x = 4
a) 21.(-35)-3.(-25).7=21.(-35)-(21.(-25)=21(-35+25)=21.(-10)=-210
b)77-11(30+7)=77-11.7+11.30=77-77-330=-330
c)85(35-27)-35(85-27)=85.35-85.27-35.85+35.27=(85.35-35.85)+(35.27-85.27)=35.27-85.27=27(35-85)=27.(-50)=-1350
d)(-25).68+(-34).(-250)=-25.68+34.2.125=-25.68+68.125=68(125-25)=68.100=6800
e)125.(-61).(-2^3).(-1)^2n+1=125.(-61).(-8).(-1)=(-8.125).61=-1000.61=-61000
h) đặt S=2100-299-298-...-22-2-1=2^100-(2^99+2^98+2^97+...+2+1)=2^100-A
ta có: A=2^99+2^98+2^97+...+2+1
2A=2^100+2^99+2^98+...+2^2+2
=>2A-A=(2^100+2^99+2^98+...+2^2+2)-(2^99+2^98+2^98+...+2+1)
=>A=2^100-1
=>S=2^100-(2^100-1)=2^100-2^100+1=1
A=2^100
a là bằng -210
ý b bằng -330
ý c bằng -1350
ý d bằng 6800
ý f bằng 225
tớ làm được 5 ý , tich nha bạn