of=>x 

however=>although

despite=>in spite

that=>x

for=>to

even=>x

to=>x

work=>working

will=>x

though=>but

studies=>study

although=>despite

are to be found=>are found

writting=>written

1. He often does exercises every night.

→ Exercises are often done by him every night

2. She usually decorates the room at weekends.

→ The room is usually decorated by her at weekends

3. Daisy always sings country songs.

→ Country songs are always sung by Daisy

4. She often gives her sister sweets.

→ Her sister is often given sweets by her

5. Nam and Peter often water these trees.

→ These trees are often watered by Nam and Peter

6. They produce cars in this country.

→ Cars are produced in this country

a: x=77+50=127

b:x=80-49=31

c: x=50/450=1/9

d: =>159-25+x=43

=>x+134=43

=>x=-91

e: =>5(2x-1)=55

=>2x-1=11

=>2x=12

=>x=6

f: =>48:x=16

=>x=3

g: =>\(x\inƯC\left(36;40\right)\)

mà x<4

nên \(x\in\left\{1;2\right\}\)

h: =>\(x\inƯC\left(24;160\right)\)

mà x>2

nên \(x\in\left\{4;8\right\}\)

i: =>5^x*625=5^25

=>5^x=5^23

=>x=23

a: A=x^2+4x+4+5

=(x+2)^2+5>=5

Dấu = xảy ra khi x=-2

b: =3/2(x^2+2/3x+2/3)

=3/2(x^2+2*x*1/3+1/9+5/9)

=3/2(x+1/3)^2+15/18>=15/18=5/6

Dấu = xảy ra khi x=-1/3

e: =x^2-2x+1+4

=(x-1)^2+4>=4

Dấu = xảy ra khi x=1

f: =2(x^2-3x)

=2(x^2-3x+9/4-9/4)

=2(x-3/2)^2-9/2>=-9/2

Dấu = xảy ra khi x=3/2

h: =-(x^2-4x-3)

=-(x^2-4x+4-7)

=-(x-2)^2+7<=7

Dấu = xảy ra khi x=2

a: =x^2+6x+9+x^2-6x+9+2x^2-32

=4x^2-14

b: =(x+3-10+x)^2=(2x-7)^2=4x^2-28x+49

c: =(x-3-x+5)^2=2^2=4

e: =x^2+10x+25-x^2+10x-25=20x

d: A=(5-1)(5+1)(5^2+1)(5^4+1)/4

=(5^2-1)(5^2+1)(5^4+1)/4

=(5^4-1)(5^4+1)/4

=(5^8-1)/4

g: =x^2-9-x^2-4x+5

=-4x-4

86712 * 482947 =41881646787

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