A) Ư(15)={1;3;5;15}

Ư(30)={1;2;3;5;6;10;15;30}

=>ƯC(15;30)={1;3;5;15}

B) B(3)={0;3;9;12;15;18;21;27}

B(6)={0;6;12;18;24;35;36;42;48}

=>BC(3;6)={0;12;18;.....}

a) (45-25).(-11)+29.(-3-17)
 = 20.(-11)+29.(-20)
 = -20.11-29.20
 = 20.(-11-29)
 = 20.(-40)
 = -800
b) (-37).(55-23)-55.(23-37)
 = (-37).32-55.(-14)
 = -1184-55.(-14)
 = -1184+770
 = -414

\(2,\frac{9}{x}=\frac{2}{5}-\frac{7}{20}\)

\(\Rightarrow\frac{9}{x}=\frac{1}{20}\)

\(\Rightarrow x=9.20\)

\(\Rightarrow x=180\)

\(\frac{x}{5}=\frac{5}{6}+\left(-\frac{19}{30}\right)\)

\(\frac{\Rightarrow x}{5}=\frac{1}{5}\)

\(\Rightarrow x=1\)

2(x - 2) - 4(3 - x) = 4

<=> 6x - 16 = 4

<=> 6x = 4 + 16

<=> 6x = 20

<=> x = 20/6 = 10/3

=> x = 10/3

3B = 3 ( 3 + 3² + .. + 3¹⁰⁰ ) 

3B = 3² + 3³ + .. + 3¹⁰¹ 

3B - B = ( 3² + 3³ + .. + 3¹⁰¹ ) - ( 3 + 3² + 3³ + ... + 3¹⁰⁰ ) 

2B = 3¹⁰¹ - 3 

B = \(\frac{3^{101}-3}{2}\)

Chúc bn hc tốt <3

     B=3+3²+3³+3⁴+...+3¹⁰⁰ 

<=>3B=3.(3+3²+3³+...+3¹⁰⁰)

           =3²+3³+3⁴+...+3¹⁰¹

<=>3B-B=(3²+3³+3⁴+...+3¹⁰¹)-(3+3²+3³+...+3¹⁰⁰⁾

<=>2B=3^101-3

 <=> B=(3¹⁰¹-3):2

Vậy B=(3¹⁰¹-3):2

Trả lời

5²=25

5³=125

5⁴=625

6²=46

6³=216

6⁴=1296

7²=49

7³=343

a) x¹⁵ = x

<=> x(x¹⁴ - 1) = 0

<=> x = 0; 1; -1

Vì số mũ là số lẻ nên x = 0; 1

=> x = 0; 1

b) như a :>