`x<3`

`->x= 1;2`

`----`

`1/5 < y/5<1`

`->1/5 < y/5<5/5`

`->y=2;3;4`

`-----`

`4/x=y/21=2/7`

\(\rightarrow\left\{{}\begin{matrix}\dfrac{4}{x}=\dfrac{y}{21}\\\dfrac{y}{21}=\dfrac{2}{7}\end{matrix}\right.\rightarrow\left\{{}\begin{matrix}\dfrac{4}{14}=\dfrac{6}{21}\\\dfrac{6}{21}=\dfrac{2}{7}\end{matrix}\right.\)

\(a.216\times y+y=3689\)

\(y\times\left(216+1\right)=3689\)

\(y\times217=3689\)

\(y=3689:217\)

\(y=17\)

\(b.y\times47-37\times y=20210\)

\(y\times\left(47-37\right)=20210\)

\(y\times10=20210\)

\(y=20210:10\)

\(y=2021\)

a)

216 * y + y = 3689

y * (216+1)=3689

y*217=3689

y=3689:217

y=17

b)

y * 47 - 37 * y = 20210

 *y (47-37)=20210

y * 10 = 20210

y = 20210 :10

y= 2021

`a)x xx96+x xx0,25=22,23`

`x xx96+x xx4=22,23`

`x xx(96+4)=22,23`

`x xx10=22,23`

`x=22,23:10=2,223`

`b)x:0,25+x xx95+x=10,23`

`x xx4+x xx95+x=10,23`

`x xx(4+95+1)=10,23`

`x xx10=10,23`

`x=10,23:10=1,023`

a: =>96x+4x=22,23

=>100x=22,23

hay x=0,2223

b: =>4x+95x+x=10,23

=>100x=10,23

hay x=0,1023

a: =>x+17,67=36,8

=>x=19,13

b: =>468:x=60

=>x=7,8

c: =>x*4,5=160,4

=>x=1604/45

d: =>100x=7856

=>x=78,56

Ta có : ax = by \(\Rightarrow\frac{x}{b}=\frac{y}{a}=\frac{x-y}{b-a}=1\left(\text{vì }x-y=b-a\right)\)

\(\Rightarrow x=b;y=a\)

Vậy x = b ; y = a

a, a.x+a.y+b.x+b.y

= a(x+y) + b(x+y) = (x+y)(a+b)=17.(-2)=-34

b, a.x-a.y+b.x-b.y

= a(x-y)+b(x-y)

=(x-y)(a+b)=-7(-1)=7

:)

a: TXĐ: D=R\{1}

b: TXĐ: D=[-2;2]\{0}

a: =>x(34,5+66,5-1)=1000

=>100x=1000

=>x=10

b: =>x*473,4=3787,2

=>x=8

c: =>136,5-x=4,5

=>x=132

d: =>x(34,56-25,56+1)=0,1

=>10x=0,1

=>x=0,01

a) a.x + a.y + b.x + b.y

= a.(x + y) + b.(x + y)

= a . 17 + b . 17

= (a +b) . 17

= -2 . 17 = -34

b) a.x - a.y + b.x - b.y

= a.(x - y) + b.(x - y)

= a . (-1) + b.(-1)

= (a + b) . (-1)

= -7 . (-1) = 7

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