He said he didn't know her address.

\(y=-sin^2x-cosx+2 \\=cos^2x-cosx+1=(cosx-\dfrac{1}{2})^2+\dfrac{3}{4}\ge\dfrac{3}{4} \\Đẳng\ thức\ xảy\ ra\ khi\ x=\dfrac{\pi}{3}+2k\pi\ (k\ nguyên) \\Vậy\ Miny=\dfrac{3}{4}\ (khi\ x=\dfrac{\pi}{3}+2k\pi\ (k\ nguyên)) \\y=-sin^2x-cosx+2 \\=cos^2x-cosx+1\le1-(-1)+1=3 \\Đẳng\ thức\ xảy\ ra\ khi\ x=\pi+2k\pi\ (k\ nguyên) \\Vậy\ Maxy=3\ (khi\ x=\pi+2k\pi\ (k\ nguyên)).\)

\(216x^6+y^3=(6x^2)^3+y^3 \\=(6x^2+y)(36x^4-6x^2y+y^2)\)

Đề đúng đấy bạn, ko sửa đâu

?

Bài 1. a) = 3xy(x - 2y)

b) = (x-11)(3x+2)

c) =  7(x + y - 1)(x - y - 1)

d) = (9x^2 + 6x + 2)(9x^2 - 6x + 2)

I. 1. easier

2. worse

3. thinner

4. as few

5. better

II. better

Câu ngược lại: I play tennis worse than my brother.

larger. Câu ngược lại: Her school is smaller than my school.

more boring.

Câu ngược lại: That film is more interesting than this film.

và worser là 1 từ ko tồn tại.

ko phải fewer nhé bạn.

\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+...+\dfrac{1}{20^2} \\>\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{20.21} \\=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{20}-\dfrac{1}{21} \\=\dfrac{1}{2}-\dfrac{1}{21}=\dfrac{19}{42}>\dfrac{18}{42}=\dfrac{3}{7}\)