Câu 12. Ngữ pháp tiếng anh 6 +........ -.......... ?.........

Cho a,b nhọn và cosa = $\frac{1}{4}$ , cosb = $\frac{1}{5}$ Tính : sin(a+b) . sin(a-b)

Bài 1: Làm tính nhân a, (x ² + 2x+1)(x+3) b, (3a+2b)(9a - 6ab+ab ²) c, (5x ² - 6y ²)(6x ² - 5y ²) Bài 2 : Làm tính nhân a,(x-y)(x ²+xy+y ²) b,(x ² - 2xy + y ² )(x-y) c, (5x ² - 2xy ²+ y ²)(-x ³ - 2x ²y+ 5xy ²) d, (2x - y)(4x ² + 2xy + y ²)(8x ³+y ³)

Cho ΔABC. Trên cạnh AB lấy 2 điểm M,N sao cho AM=AN=NB. Từ M và N kẻ các đg song ² với BC chúng cắt cạnh AC tại M' và N' Tính NN' và BC biết MM' = 5cm

Rút gọn P = sinx ( 1 + 2.cos2x + 2.cos4x + 2.cos6x )

Cho các CTHH sau: Na2O, P2O5, KOH, HCl, H2SO4, SO2, Fe3O4, Mg(OH)2, Ba(HCO3)2, HgO, H2S, Al2(SO4)3 - Hãy cho biết CTHH nào là oxit axit? Bazơ? Muối? - Gọi tên mỗi chất

Biến đổi thành tổng : 4.cosa.cos2a. sin$\frac{5a}{2}$

I.Sửa lỗ sai: 1.Millions of people have visit Disney World in Orlando,Florida,since it opened 2.Gertrude Stein,a well -know American novelist ,was born in1874 and has died in 1946 3.At summer camp last year children swam,rode horses and were playing baseball 4.Student who did not brought pencils to the test were not allowed to take it 5.Television was very popular in the United States since the fifties 6.Inspiring by her example,other zoologists have begun working with apes in the wild 7.This is the first time T tried to play badminton 8.None of the pictures are the same .They are all very different with each other 9.The last time we decorated the flat was 5 years ago.The flat wasn't decorated for five years 10.In the end,the result was quite different with what we expected HỘ MK ZỚIIIIII

Trong ΔABC, CMR : cos2A + cos2B + cos2C + 1 = -4.cosA.cosB.cosC

Phân tích đa thức sau:x^4+10x^3+26x^2+10x+1 (Đề ko sai nha mn)