Có dấu ngoặc ở đâu ko?

Có phải ý bn là thế này ko:

\(\frac{19^{100}+19^{96}+19^{92}+...+19^4+1}{19^{102}+19^{100}+19^{98}+...+19^2+1}\)

đởn giản  chúng đều= nhau

\(\frac{19^{100}+1}{19^{99}+1}< \frac{19^{100}+1+18}{19^{99}+1+18}=\frac{19.\left(19^{99}+1\right)}{19.\left(19^{98}+1\right)}=\frac{19^{99}+1}{19^{98}+1}\)

\(\Rightarrow A< B\)

Vậy A<B

k minh nha

Ta có : \(A=100+98+...+2-97-...-1\)

=> \(A=100+\left(98-97\right)+...+\left(2-1\right)\)

=> \(A=100+1+...+1\)

=> \(A=100+1.49=100+49=149\)

A=100+98+96+...+2-97-95-...-1

A=100+(98-97)+(96-95)+...+(2-1)

A=100+1+1+...+1

A=100+1.49

A=100+49

A=149

b)Tận cùng=5 hoặc 0 nhưng mình ngại viết lắm,thông cảm nha

a. = 6.

1) 123. 456456-456.123123

= 123. 123123.2 - 123. 123123.2

= 0

2) 127.313313-13.127127

= 127. 313.1001 - 13. 1001.127

= 127127.313 - 13.127127

= 127127. ( 313-13) 

=127127.300 = 38138100

3) (98.7676-9898.76).(1+2+3+......+100)

= (98. 101.76 - 98.101.76).(1+2+3+......+100)

= 0 .(1+2+3+........+100)

=0

4) 19 + 19 +......+19+77+77+....+77

= 19x 23 + 77 x19 

= 19 x ( 23+77) 

= 19 x 100

= 1900 

\(\dfrac{7}{19}x\dfrac{8}{23}+\dfrac{7}{19}x\dfrac{15}{23}+1\dfrac{7}{19}\)

= \(\dfrac{7}{19}x\left(\dfrac{8}{23}+\dfrac{15}{23}\right)+1+\dfrac{7}{19}\)

=\(\dfrac{7}{19}x1+1+\dfrac{7}{19}\)

= \(\dfrac{7}{19}+1+\dfrac{7}{19}=1\dfrac{14}{19}\) = \(\dfrac{33}{19}\)

\(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{3}{21}-\dfrac{17}{32}\)

=  \(\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{1}{7}-\dfrac{17}{32}\)

= \(\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{49}{32}-\dfrac{17}{32}\right)\)

= 1 + 1 + 1 = 3

\(\dfrac{8}{9}x\dfrac{15}{16}x\dfrac{24}{25}x\dfrac{35}{36}x\dfrac{48}{49}x\dfrac{63}{64}\)

= \(\dfrac{3}{4}\) *Câu này bạn tự sử dụng gạch nhé!

`1,`

`a,`

`7/19 \times 8/23 + 7/19 \times 15/23 + 1 7/19`

`= 7/19 \times 8/23 + 7/19 \times 15/23 + 1 + 7/19`

`= 7/19 \times (8/23 + 15/23 + 1) + 1`

`= 7/19 \times 2 + 1`

`=14/19 + 1`

`= 33/19`

`b,`

`75/100 + 18/21 + 49/32 + 1/4 + 3/21 - 17/32`

`= 75/100 + (18/21 + 3/21) + (49/32 - 17/32) + 1/4`

`= 0,75 + 1 + 1 + 0,25`

`= (0,75 + 0,25) + 1 + 1`

`= 1+1+1=3`

`c,`

`8/9 \times 15/16 \times 24/25 \times 35/36 \times 48/49 \times 63/64`

`=` \(\dfrac{2\times3}{3\times3}\times\dfrac{3\times5}{4\times4}\times\dfrac{3\times4\times2}{5\times5}\times\dfrac{5\times7}{6\times6}\times\dfrac{6\times8}{7\times7}\times\dfrac{7\times9}{8\times8}\)

`= 3/4` (bạn sử dụng gạch, rút gọn các số là được nhé).