Chứng minh rằng:

A= 2²+ 2³+2⁴+...+2¹²¹ chia hết cho 3, cho 7

mn giúp ẻm nhoa??!!!

Help me, please !!!!

Tìm số nguyên x, biết:

a, (-4).|x+2|= -8

b, 4.|x+1|= 8.(-2)-8.(-5)

c, (2.x-4).(x+6)=0

d,4.(x-5)-3(x+7)= -19

e, 3.(x-4)-(8-x)=12

f, 7.(x-3)-5.(3-x)=11.x-5

I, Write an email of about 80 to your friend. Tell him/ her about your favouirte room in the house. Use the following guidance:

- What is the favouirte room in your house? (living room, bedroom, your room, ...)

-Describe it

-Why is it your favouirte room?

II, Write a passage from 80-100 words to your school

Giải:
Cả 3 bạn có số cây kẹo là:
 8 + 5 + 4 = 17 ( cây )
        Đáp số: 17 cây kẹo