Hello everyone, my name is Le Ngoc Diep. This year I am 12 years old, I live in Dong Da, Hanoi. There are four members in my family, including my parents, elder brother and me. Now, I am studying in class 9B at Chu Van An school. At school I have a lot of friends, they are all docile and lovely. Everyone says that I am a very active and energetic child so they love me so much. My favorite subject is Physics and English. My hobbies are cooking and reading books. Some of the favorite books are science fiction, detective, history and art. In my spare time, I also take an online piano course. In the future, I will try to get more experience to pursue the dream of becoming a famous pianist performing in the world.

cạnh hình vuông là:64:8=8(cm)

chui vi hình vuông là:8x4=32(cm)

ĐS:32cm

Xin chao hom nay mik se to chuc cuoc thi "Ai tich nhanh nhat ".

Cuoc thi gom 2 phan:+)P1:vong tuyen

+)P2:vong chung ket

Chinh su vo cam cua cac bn da tao ra cuoc thi nay!!!Mik tin chac nhung ban nay se duoc vao vong 2:

+)Trang Moon

+)@$Mr.VôDanh$

+)@Love Music Nightcore

+)Nguyen Ba Huy

+)Manh Ngo Van

+)Bùi Thị Tính

+)Nguyenquanghuy

+)@Satoshi

+)@Linh Đào

+)qfffffffffff

+)Tu Vu

+)Tuyen Vu

+)b. ong bong

+)@sakura Kiemono

Chuc cac ban thi tot!!!<3<3

100+100=200 

k cho anh nhé

Y H dung.Vi thi hk II la tu hoc neu ban hok bai thi bn A se tu bt lam va ko can di xem boi,ko xin the de bt truoc ket qua thi cua mik.Neu em la A thi em se nghe loi bn va se co gang hoc tap,hok bai de ki thi nay dat dc kq cao nhat co the!

2+2=4

học giỏi nhé em

Hướng dẫn giải:

 a) A = 3x + 2 + |5x|

=> A = 3x + 2 + 5x khi x ≥ 0

     A = 3x + 2 - 5x khi x < 0

Vậy A = 8x + 2 khi x ≥ 0

      A = -2x + 2 khi x < 0

b) B = 4x - 2x + 12 khi x ≥ 0

    B = -4x -2x + 12 khi x < 0

Vậy B = 2x + 12 khi x ≥ 0

      B = -6x khi x < 0

c) Với x > 5 => x - 4 > 1 hay x - 4 dương nên

C = x - 4 - 2x + 12 = -x + 8

Vậy với x > 5 thì C = -x + 8

d) D= 3x + 2 + x+ 5 khi x + 5 ≥ 0

    D = 3x + 2 - (x + 5) khi x + 5 < 0

Vậy D = 4x + 7 khi x ≥ -5

      D = 2x - 3 khi x < -5