Ta có :

\(T=\left(\dfrac{1}{2}+1\right)\left(\dfrac{1}{3}+1\right)\left(\dfrac{1}{4}+1\right)...............\left(\dfrac{1}{99}+1\right)\)

\(T=\left(\dfrac{1}{2}+\dfrac{2}{2}\right)\left(\dfrac{1}{3}+\dfrac{3}{3}\right)\left(\dfrac{1}{4}+\dfrac{4}{4}\right)................\left(\dfrac{1}{99}+\dfrac{99}{99}\right)\)

\(T=\dfrac{3}{2}.\dfrac{4}{3}.\dfrac{5}{4}...................\dfrac{100}{99}\)

\(T=\dfrac{1}{2}.\dfrac{100}{1}=\dfrac{100}{2}=50\)

Học tốt nhs!

bn ơi bài 4 làm kiểu gì zậy

x = 6 - 3

x = 3

Bài làm

Vì | x + 3 | = 6

\(\Rightarrow\hept{\begin{cases}x+3=6\\x+3=-6\end{cases}\Rightarrow\hept{\begin{cases}x=3\\-9\end{cases}}}\)

Vậy x=3 hoặc x=-9

# Chúc bạn học tốt #

ta có \(|x+3|=6\)

suy ra \(\orbr{\begin{cases}x+3=6\\x+3=-6\end{cases}}\)

suy ra \(\orbr{\begin{cases}x=3\\x=-9\end{cases}}\)

tích nha

Bút ký: là một thể của ký, nằm trung gian giữa ký sự và tùy bút. Bút ký thiên về ghi lại một cảnh vật mà nhà văn mắt thấy tai nghe, thường trong các chuyến đi. Bút ký tái hiện con người và sự việc một cách phong phú, sinh động, nhưng qua đó biểu hiện khá trực tiếp khuynh hướng cảm nghĩ của tác giả, có màu sắc trữ tình. Kết hợp linh hoạt các phương thức nghị luận, tự sự, trữ tình nhưng tùy theo độ đậm nhạt khác nhau của các phương thức mà ta có bút ký chính luận, bút ký tùy bút ,.................

2/3:x/5+5/7=10/21+10/9

2/3:x/5+5/7=100/63

2/3:x/5= 100/63-5/7=55/63

x/5= 2/3:55/63

x/5= 42/55

x=42/55 *5

x=42/11

* là nhân đó

KO THẤY GÌ

biết j bn 

X đó kìa, tìm làm j

\(A=\frac{55}{11.16}+\frac{55}{16.21}+\frac{55}{21.26}+\frac{55}{26.31}+\frac{55}{31.36}+\frac{55}{36.41}\)

\(A=\frac{55}{5}\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+...+\frac{1}{36}-\frac{1}{41}\right)\)

\(A=11\left(\frac{1}{11}-\frac{1}{41}\right)\)

\(A=11.\frac{30}{451}\)

\(A=\frac{30}{41}\)

Ta có : 

\(=5\left(\frac{5}{11.16}+\frac{5}{16.21}+\frac{5}{21.26}+\frac{5}{26.31}+\frac{5}{31.36}+\frac{5}{36.41}\right)\)

\(=5\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+.....+\frac{1}{36}-\frac{1}{41}\right)\)

 \(=5\left(\frac{1}{11}-\frac{1}{41}\right)\)

\(=5\left(\frac{30}{451}\right)=\frac{150}{451}\)

\(A=\frac{55}{11.16}+\frac{55}{16.21}+...+\frac{55}{32.36}+\frac{55}{36.41}\)

\(A=\frac{55}{5}.\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+....+\frac{1}{32}-\frac{1}{36}+\frac{1}{36}-\frac{1}{41}\right)\)

\(A=11.\left(\frac{1}{11}-\frac{1}{42}\right)=11.\frac{31}{462}=\frac{31}{42}\)

-Yesterday,my three brothers and I (1)....started........(start)painting the down-stairs rooms.Unfortunately while I (2).....was mixing.........(mix)the paint,one of my sisters (3)......opened....(open)the door.Nobody (4)...told..(tell)her that we (5)....were.....(be)in the room,you see.So instead of painting the walls,we (6)......spent......(spend)all morning cleaning the paint off the floor.But worse things(7).....was dripping......(drip)through the ceiling next to my bed.We (10).........had spent.........(spend)the day so far repairing the roof.

1/Put each verb in brackets into a suitable tense:

Yesterday, my three brothers and I (1)......started......(start)painting the down-stairs rooms.Unfortunately while I (2).......was mixing.......(mix)the paint, one of my sisters (3).....opened.....(open)the door.Nobody (4)..told...(tell) her that we (5)....were.....(be)in the room,you see.So instead of painting the walls, we (6)......spent......(spend)all morning cleaning the paint off the floor.But worse things(7)......was dripping......(drip)through the ceiling next to my bed.We (10).........had spent.........(spend)the day so far repairing the roof.

Chúc bạn học tốt!

Yesterday,my three brothers and I (1)......started......(start)painting the down-stairs rooms.Unfortunately while I (2)......was mixing........(mix)the paint,one of my sisters (3).....opened.....(open)the door.Nobody (4).told....(tell)her that we (5).....were....(be)in the room,you see.So instead of painting the walls,we (6)......spent......(spend)all morning cleaning the paint off the floor.But worse things(7)......was dripping......(drip)through the ceiling next to my bed.We (10)..........have spent........(spend)the day so far repairing the roof.