A=1+3+3^2+3^3+3^4+...+3^100

3A=3+3^2+3^3+3^4+...+3^101

3A-A=(3+3^2+3^3+3^4+...+3^101)-(1+3+3^2+3^3+3^4+...+3^100)

2A=3^101-1

A=(3^101-1):2

phần b làm tương tự phần a nhưng mà là nhân cả biểu thức B với 4 nhé

a)5²+12²=169 =13²

b)8²+15²=289=17²

\(5^2+12^2=169\) ko la so chinh phuong vi \(169⋮\)\(1\), \(13;169\)

\(8^2+15^{12}=289\) ko la so chinh phuong vi \(289⋮1;17;289\)

chu y so chinh phuong chi chia het cho 1 va chinh no

5 mũ 2 + 12 mũ 2= 25+144=169=13 mũ 2( phải)

8 mũ 2 + 15 mũ 2= 64+225=289=17 mũ 2(phải)

a,3²+4²=9+16=25=5²  là số chính phương

b,5²+12²=25+144=169=13² là số chính phương

cảm ơn bạn nha

a) 3² + 4² = 9 + 16 = 25 = 5²

b) 5² + 12² = 25 + 144 = 169 = 13²

a) Ta có :

\(27^{27}>27^{26}=\left(27^2\right)^{13}=729^{13}>243^{13}\)

\(\Rightarrow27^{27}>243^{13}\)

\(\Rightarrow-27^{27}< -243^{13}\)

\(\Rightarrow\left(-27\right)^{27}< \left(-243\right)^{13}\)

b) \(\left(\dfrac{1}{8}\right)^{25}>\left(\dfrac{1}{8}\right)^{26}=\left(\dfrac{1}{8^2}\right)^{13}=\left(\dfrac{1}{64}\right)^{13}>\left(\dfrac{1}{128}\right)^{13}\)

\(\Rightarrow\left(\dfrac{1}{8}\right)^{25}>\left(\dfrac{1}{128}\right)^{13}\)

\(\Rightarrow\left(-\dfrac{1}{8}\right)^{25}< \left(-\dfrac{1}{128}\right)^{13}\)

c) \(4^{50}=\left(4^5\right)^{10}=1024^{10}\)

\(8^{30}=\left(8^3\right)^{10}=512^{10}< 1024^{10}\)

\(\Rightarrow4^{50}>8^{30}\)

d) \(\left(\dfrac{1}{9}\right)^{17}< \left(\dfrac{1}{9}\right)^{12}< \left(\dfrac{1}{27}\right)^{12}\)

\(\Rightarrow\left(\dfrac{1}{9}\right)^{17}< \left(\dfrac{1}{27}\right)^{12}\)

a) Ta có :

2727>2726=(272)13=72913>243132727>2726=(272)13=72913>24313

⇒2727>24313⇒2727>24313

⇒−2727<−24313⇒−2727<−24313

⇒(−27)27<(−243)13⇒(−27)27<(−243)13

b) (18)25>(18)26=(182)13=(164)13>(1128)13(81​)25>(81​)26=(821​)13=(641​)13>(1281​)13

⇒(18)25>(1128)13⇒(81​)25>(1281​)13

$\Rightarrow$