b: 30 chia hết cho x

45 chia hết cho x

Do đó: \(x\inƯC\left(30;45\right)=Ư\left(15\right)\)

mà x>10

nen x=15

c: \(\Leftrightarrow x+2\in\left\{1;-1;3;-3;9;-9\right\}\)

hay \(x\in\left\{-1;-3;1;-5;7;-11\right\}\)

d: =>x+3+14 chia hết cho x+3

=>\(x+3\in\left\{1;-1;2;-2;7;-7;14;-14\right\}\)

hay \(x\in\left\{-2;-4;-1;-5;4;-10;11;-17\right\}\)

\(a,\dfrac{52}{32}=\dfrac{13}{8}\\ \dfrac{55}{65}=\dfrac{11}{13}\\ MSC:104\\ =>\dfrac{13}{8}=\dfrac{13.13}{8.13}=\dfrac{169}{104}\\ \dfrac{11}{13}=\dfrac{11.8}{13.8}=\dfrac{88}{104}\)

\(b,\dfrac{72}{64}=\dfrac{9}{8}\\ \dfrac{54}{81}=\dfrac{2}{3}\\ MSC:24\\ \dfrac{9}{8}=\dfrac{9.3}{8.3}=\dfrac{27}{24}\\ \dfrac{2}{3}=\dfrac{2.8}{3.8}=\dfrac{16}{24}\\ c,\dfrac{24}{36}=\dfrac{2}{3}\\ \dfrac{12}{30}=\dfrac{2}{5}\\ MSC:15\\ \dfrac{2}{3}=\dfrac{2.5}{3.5}=\dfrac{10}{15}\\ \dfrac{2}{5}=\dfrac{2.3}{3.5}=\dfrac{6}{15}\)

\(d,\dfrac{80}{40}=2\\ \dfrac{45}{63}=\dfrac{5}{7}\\ MSC:7\\ 2=\dfrac{14}{7}\\ e,\dfrac{150}{50}=3\\ \dfrac{100}{200}=\dfrac{1}{2}\\ MSC:2\\ 3=\dfrac{6}{2}\\ f,\dfrac{54}{81}=\dfrac{2}{3}\\ \dfrac{69}{93}=\dfrac{23}{21}\\ MSC:21\\ \dfrac{2}{3}=\dfrac{2.7}{3.7}=\dfrac{14}{21}\)

\(a.\dfrac{52}{32}\text{=}\dfrac{13}{8};\dfrac{55}{65}\text{=}\dfrac{11}{13}\)

\(\dfrac{13.13}{13.8}\text{=}\dfrac{169}{104};\dfrac{11.8}{13.8}\text{=}\dfrac{88}{104}\)

\(c.\dfrac{24}{36}\text{=}\dfrac{2}{3};\dfrac{12}{30}\text{=}\dfrac{2}{5}\)

\(\dfrac{2.5}{3.5}\text{=}\dfrac{10}{15};\dfrac{2.3}{5.3}\text{=}\dfrac{6}{15}\)

\(b.\dfrac{72}{64}\text{=}\dfrac{9.3}{8.3}\text{=}\dfrac{27}{24};\dfrac{54}{81}\text{=}\dfrac{2.8}{3.8}\text{=}\dfrac{16}{24}\)

\(d.\dfrac{80}{40}\text{=}\dfrac{2.63}{63}\text{=}\dfrac{126}{63};\dfrac{45}{63}\)

\(e.\dfrac{150}{50}\text{=}\dfrac{3.2}{2}\text{=}\dfrac{6}{2};\dfrac{100}{200}\text{=}\dfrac{1}{2}\)

\(f.\dfrac{54}{81}\text{=}\dfrac{2.31}{3.31}\text{=}\dfrac{62}{93};\dfrac{69}{93}\)

45 và 72 = 45 : 72 x 100 = 62,5%

16 và 80 = 16 : 80 x 100 = 20%

15,3 và 30 = 15,3 : 30 x 100 = 51%

8,4 và 5,6 = 8,4 : 5,6 x 100 = 150%

45 và 72 là 62,5%
15,3 và 30 là 51%
16 và 80 là 20%
8,4 và 56 là 15%

1/ 45:72=0,625=62,5% 2/ 15,3:30=0,51=51% 3/ 16:80=0,2=20% 4/ 8,4:56=0,15=15%

a: \(24=2^3\cdot3;40=2^3\cdot5\)

=>\(ƯCLN\left(24;40\right)=2^3=8\)

=>\(ƯC\left(24;40\right)=\left\{1;-1;2;-2;4;-4;8;-8\right\}\)

b: \(12=2^2\cdot3;52=2^2\cdot13\)

=>\(ƯCLN\left(12;52\right)=2^2=4\)

=>\(ƯC\left(12;52\right)=\left\{1;-1;2;-2;4;-4\right\}\)

c: \(45=3^2\cdot5;180=2^2\cdot3^2\cdot5\)

=>\(ƯCLN\left(45;180\right)=3^2\cdot5=45\)

=>\(ƯC\left(45;180\right)=\left\{1;-1;3;-3;5;-5;9;-9;15;-15;45;-45\right\}\)

d: \(27=3^3;45=3^2\cdot5;75=3\cdot5^2\)

=>\(ƯCLN\left(27;45;75\right)=3\)

=>\(ƯC\left(27;45;75\right)=\left\{1;-1;3;-3\right\}\)

hừ 

B

A

C

100

B

C

a) A>B

b) 72*45-72*44=72*44-72*43 ; 2*500=5*200

* là lũy thừa nha mấy chế