125 \(\times\) y - 12 \(\times\)y - 13 \(\times\) y = 5208000

y \(\times\)( 125 - 12 - 13) = 5208000

y \(\times\) 100 = 52008000

y = 5208000 : 100

y = 52080

125.y-12.y-13.y=5208000

(125-12-13).y=5208000

100.y=5208000

y=5208000:100

y=52080

125 x y - 12 x y - 13 x y = 5208000

y x (125 - 12 - 13) = 5208000

y x 100 = 5208000

y = 5208000 : 100

y = 52080

vậy ...

`125×y−12×y−13×y=520800`

`(125−12−13)×y=520800`

`100×y=520800`

`y=520800:100`

`y=5208`

Vậy` y=5208`

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128 x y - 12 x y - 16 x y = 5208000

(128 - 12 - 16) x y          = 5208000

100 x y                         = 5208000

         y                         = 5208000 : 100

         y                         = 520800

bài 1: x.(x+7) = 0

Th1:x=0              Th2:x+7=0

                          =>x=-7

bài 2 (x+12).(x-3)= 0

Th1:x+12=0                                         Th2:x-3=0

=>x=-12                                                =>x=3

bài 3 (-x+5).(3-x)=0

Th1 (-x)+5=0                                          Th2:3-x=0

=>-x=-5                                                  =>x=3

bài 4 x.(2+x).(7-x)=0

Th1:x=0                                               Th3:7-x=0

Th2:2+x=0                                             =>x=7

=>x=-2

bài 5 (x-1).(x+2).(-x-3)=0

Th1:x-1=0                                               Th2:x+2=0

=>x=1                                                   =>x=-2

Th3:-x-3=0

=>-x=-3

C

Ta có: \(\dfrac{x}{2}=\dfrac{y}{3}=k\)

\(\Rightarrow x=2k,y=3k\)

Mà: \(x\cdot y=6\)

\(\Rightarrow2k\cdot3k=6\)

\(\Rightarrow6k^2=6\)

\(\Rightarrow k^2=\dfrac{6}{6}=1\)

\(\Rightarrow k=1\)

 Từ đó ta tìm được x và y:

\(\dfrac{x}{2}=1\Rightarrow x=2\)

\(\dfrac{y}{3}=1\Rightarrow y=3\)