\(A=\frac{2^{30}.5^7+2^{13}.5^{27}}{2^{27}.5^7+2^{10}.5^{27}}\)

\(=\frac{2^3\left(2^{27}.5^7+2^{10}.5^{27}\right)}{2^{27}.5^7+2^{10}.5^{27}}\)

\(=2^3=8\)

\(\frac{2^{30}.5^7+2^{13}.5^{27}}{2^{27}.5^7+2^{10}.5^{27}}+\frac{2^{13}.5^7\left(2^{17}+5^{20}\right)}{2^{10}.5^7\left(2^{17}+5^{20}\right)}=2^3=8\)

a. Vì \(\left|3x-2\right|\ge0\forall x\)

\(\Rightarrow2\left|3x-2\right|-1\ge-1\)

Dấu "=" xảy ra \(\Leftrightarrow2\left|3x-2\right|=0\Leftrightarrow3x-2=0\Leftrightarrow x=\frac{2}{3}\)

Vậy Amin = - 1 <=> x = 2/3

b. Vì \(\left|x-4x\right|\ge0\forall x\)

\(\Rightarrow5\left|1-4x\right|-1\ge-1\)

Dấu "=" xảy ra \(\Leftrightarrow5\left|1-4x\right|=0\Leftrightarrow1-4x=0\Leftrightarrow x=\frac{1}{4}\)

Vậy Bmin = - 1 <=> x = 1/4

c. Vì \(x^2\ge0\forall x;\left|y-2\right|\ge0\forall y\)

\(\Rightarrow x^2+3\left|y-2\right|-1\ge-1\)

Dấu "=" xảy ra \(\Leftrightarrow\orbr{\begin{cases}x^2=0\\3\left|y-2\right|=0\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=0\\y-2=0\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=0\\y=2\end{cases}}\)

Vậy Cmin = - 1 <=> x = 0 ; y = 2

d. Vì \(\left|x\right|\ge0\forall x\)\(\Rightarrow x+\left|x\right|\ge0\forall x\)

Dấu "=" xảy ra <=> x bé hơn hoặc bằng 0

Vậy Dmin = 0 <=> x bé hơn hoặc bằng 0

e.

+) Nếu x > hoặc bằng 7

=> E = | x - 7 | + 6 - x = x - 7 + 6 - x = -1

Vậy x > hoặc bằng 7 thì E có một giá trị duy nhất là -1

+) Nếu 0 < x < 7

=> E = | x - 7 | + 6 - x = - x + 7 + 6 - x = - 2x + 13 ( nhỏ nhất bằng 1 <=> x = 6 )

+) Nếu x bé hơn hoặc bằng 0

=> E = | x - 7 | + 6 - x = - x + 7 + 6 + x = 13  

Vậy Emin = -1 <=> x lớn hơn hoặc bằng 7

Ta có : \(2S=2^2+2^3+2^4+...+2^{201}\)

\(< =>S=2+2^2+2^3+...+2^{200}\)

Nên \(2S-S=\left(2^2+2^3+2^4+...+2^{201}\right)-\left(2+2^2+2^3+...+2^{200}\right)\)

\(< =>S=2^{201}-2< =>2S=2^{202}-4\)

Vậy \(2S=2^2+2^3+2^4+...+2^{201}=2^{202}-4\)

s2=2 mũ 202 -4

- 5x = 46 - 16 - ( - 60 )

=> - 5x = 30 + 60

=> - 5x = 90

=> x = - 18

\(-5x=46-16-\left(-60\right)\)

\(-5x=30+60\)

\(-5x=90\)

\(x=90:\left(-5\right)\)

\(x=-18\)

Học tốt

a, There is some milk.

b, Her birthday is in March.

c, Today is the ninth of May.

d, How many desks are there?

e, Let's go shopping.

                        Chúc bạn học tốt nhé!

a, There are some milk => is

b, Her birthday is on March => in

c, Today is the nine of may => nineth

d, How many desk are there => desks

e, Let's going shopping =>go

Ex.1

1. Where is your mother ?

2. It is about two kilometers from my house to Asia Park

3. You should see a doctor

Ex.2

1.B. works

2.B. scratch your face

3 B. class

Ex.3 thì bạn tự viết nhé :) 

Ex 1:  Reorder the sentences:

1. Mother / is / Where / your / ? /

=>Where is your mother ?

2.  to Asia Park / from my house / two kilometers / it / is /about /./

=>It is from my house to Asia Park about two kilometers

3.a doctor / should / You / see/ . /

=>You should see a doctor

Ex 2: Circle:

1. My mother is a nurse. She ......... in a hospital.

A. working           B. works               C.  work

2.You should ' t play with a cat because it may........................

A. cut yourself          B. Scratch your face          C. Fell down

3.  She study in ............ 5a².

A. football                    B. class                     C. eat

Ex 3 : Write about your Family.

Tự viết