Gọi số hạng thứ nhất, thứ hai là a, b khi đó:

\(10a+b=4263\)

\(a+b=1356\)

\(\Rightarrow9a=10a+b-a-b=4263-1356=2907\)

\(\Rightarrow a=2907:9=323\)

Vậy số hạng thứ nhất là 323

\(a,Ư\left(199\right)=\left\{1;199\right\}\\ B,Ư\left(625\right)=\left\{1;5;25;625\right\}\\ c,Ư\left(200\right)=\left\{1;2;4;5;8;10;20;25;40;50;100;200\right\}\)

a,Ư(199)={1;199} 
 

b,Ư(625)={1;5;25;625} 
 

c,Ư(200)={1;2;4;5;8;10;20;25;40;50;100;200} 

\(Ư\left(90\right)=\left\{\text{1,2,3,5,6,9,10,15,18,30,45}\right\}\) 11 ước

\(Ư\left(540\right)=\left\{\text{1,2,3,4,5,6,9,10,12,15,18,20,27,30,36,45,54,60,90,108,135,180,270}\right\}\)

23 ước

\(Ư\left(3675\right)=\left\{\text{1,3,5,7,15,21,25,35,49,75,105,147,175,245,525,735,1225}\right\}\)

17 ước

a. 90 = 2.3.3.5 

Số ước là: 

(1 + 1) x (2 +1) x ( 1 + 1) = 12 

b. 540 = 2.2.3.3.5

Số ước là: 

(2+1).(3+1).(1+1) = 24 

c. 3675 = 3.5.5.7.7

Số ước là: 

( 1 + 1).(2+1).(2+1) = 18 ước 

\(4578=2\cdot3\cdot7\cdot109\)

\(22725=3^2\cdot5^2\cdot101\)

\(478=2\cdot239\)

212 ⋮ 2

522 ⋮ 2

Vậy (212 + 522) ⋮ 2

\(212⋮2\)

\(522⋮2\)

\(\Rightarrow512+522⋮2\)

\(3^4.3^x=3^7\\ \Rightarrow4+x=7\\ \Rightarrow x=3.\)

\(3^4.3^x=3^7\)

\(81.3^x=2187\)

\(3^x=2187:81\)

\(3^x=27\)

\(\Rightarrow3^2=27\)

\(\Rightarrow x=2\)

\(\left(2x+1\right)^3=125\\ \Rightarrow\left(2x+1\right)^3=5^3\\ \Rightarrow2x+1=5\\ \Rightarrow2x=4\\ \Rightarrow x=2.\\ b,\left(2x-1\right)^4=16\\ \Rightarrow\left(2x-1\right)^4=2^4\\ \Rightarrow2x-1=2\\ \Rightarrow2x=3\\ \Rightarrow x=\dfrac{3}{2}.\\ c,6.3^x-2.3^x=36\\ \Rightarrow3^x.\left(6-2\right)=36\\ \Rightarrow3^x.4=36\\ \Rightarrow3^x=9\\ \Rightarrow3^x=3^2\\ \Rightarrow x=2.\\ d,2^{x+1}-2^x=32\\ \Rightarrow2^x.\left(2-1\right)=32\\ \Rightarrow2^x=2^5\\ \Rightarrow x=5.\)

\(a,91-5.\left(5+x\right)=61\\ \Rightarrow=5.\left(5+x\right)=30\\ \Rightarrow5+x=6\\ \Rightarrow x=1.\\ b,\left[195-\left(3x-27\right)\right].39=4212\\ \Rightarrow195-\left(3x-27\right)=108\\ \Rightarrow3x-27=87\\ \Rightarrow3x=114\\ \Rightarrow x=38.\)

\(91-5.\left(5+x\right)=61\)

\(\Rightarrow5.\left(5+x\right)=91-61\)

\(\Rightarrow5.\left(5+x\right)=30\)

\(\Rightarrow5+x=\dfrac{30}{5}=6\)

\(\Rightarrow x=6-5=1\)

\(\left[195-\left(3x-27\right)\right].39=4212\)

\(\Rightarrow195-3x+27=\dfrac{4212}{39}=108\)

\(\Rightarrow222-3x=108\)

\(\Rightarrow3x=222-108=114\)

\(\Rightarrow x=\dfrac{114}{3}=38\)

\(a,250:\left(10-x\right)=25\\ \Rightarrow10-x=10\\ \Rightarrow x=0.\\b,3x-2018:2=23\\ \Rightarrow3x-1009=23\\ \Rightarrow3x=1032\\ \Rightarrow x=344. \)

a) \(250:\left(10-x\right)=25\)

\(10-x=250:25\)

\(10-x=10\)

\(x=10-10\)

\(x=0\)

b) \(3x-2018:2=23\)

\(3x-1009=23\)

\(3x=23+1009\)

\(3x=1032\)

\(x=1032:3\)

\(x=344\)