nhìu dữ, nhưg liệu có ****?

câu này dễ quá,chẳng muốn giải

ko bít chứ j

a) 160 - ( 2³ . 5² - 6 . 25 ) = 160-( 8 . 25 - 6 . 25 ) = 160 - ( 25 . ( 8-6)) = 160-(25 . 2) = 160- 50 = 110

b) 4 . 5² - 32 : 2⁴  = 4 . 25 - 4 . 8 : 16 = 4 . ( 25 - 8 : 16 ) = 4 . 24,5 = 98

777 : 7 + 1331 : 11³

= 777:7+1331:1331

⁼¹¹¹⁺¹

⁼¹¹²

4 . 5² - 32 . 2⁴

= 2² . 5² - 2³ . 2² . 2⁴

= ( 2 . 5 )² - 2³⁺²⁺⁴

= 10² - 2⁹

= -412

a, =  36 : 4 + 2 . 25 

= 9 + 50

=  59 

b , = 5 . 16 - 18 : 9

= 80 - 2 

78

a, =  36 : 4 + 2 . 25 

= 9 + 50

=  59 

b , = 5 . 16 - 18 : 9

= 80 - 2 

78

b ) \(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}\)

= 1 - 1/2 + 1/2 - 1/3 + ... + 1/99 - 1/100

= 1 - 1/100

= 99/100

c ) Đặt A = \(\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{100^2}\)

=> A < \(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{99.100}\)

=> A < 1 - 1/2 + 1/2 - 1/3 + ... + 1/99 - 1/100= 1 - 1/100 = 99/100 < 1

Vậy \(\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{100^2}\)< 1

b, \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{98.99}+\)\(\frac{1}{99.100}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}\)

\(=1-\frac{1}{100}\)

\(=\frac{99}{100}\)

c,Ta thấy

\(\frac{1}{2^2}< \frac{1}{1.2}\)

\(\frac{1}{3^2}< \frac{1}{2.3}\)

\(\frac{1}{4^2}< \frac{1}{3.4}\)

\(.....\)

\(\frac{1}{100^2}< \frac{1}{99.100}\)

\(\Rightarrow\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{100^2}\)\(< \frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)

                                                                             \(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)

                                                                               \(=1-\frac{1}{100}< 1\)

\(\Rightarrow\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{100^2}< 1\left(đpcm\right)\)

a) 125 + 70 + 375 + 230 = (125 + 375) + (70 + 230) = 500 + 300 = 800

b) 6² : 4 . 3 + 2 . 5² = 6² : 2² . 3 + 2 . 25 = 3² . 3 + 50 = 3³ + 50 = 27 + 50 = 77

c) 150 : [25 . (18 - 4²)] = 150 : (25 . 2) = 150 : 50 = 3

Câu b:

B = (3\(^{10}\).11 + 3\(^{10}\).5) : (3\(^9\).2\(^4\))

B = 3\(^{10}\).(11 + 5): (3\(^9\).2\(^4\))

B = 3\(^{10}\).16:(3\(^9\).2\(^4\))

B = (3\(^{10}\) : 3\(^9\)).(16 : 2\(^4\))

B = 3.1

B = 3

Câu c:

C = (2\(^{10}\).13 + 2\(^{10}\).65) : (2\(^8\).104)

C = 2\(^{10}\).(13 + 65):(2\(^8\).104)

C = 2\(^{10}\).78 : (2\(^8\).104)

C = (2\(^{10}\) : 2\(^8\)).(78 : 104)

C = 2\(^2\).\(\frac34\)

C = 3