Question

4 пример.
Заранее спасибо.​

Answer 1

Ответ:

Объяснение:

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Answer 2

$\displaystyle \tt 30(1,8-y)^2+20(y+1,8)(y-1,8)=50y^2+140,4\\\displaystyle \tt 30(3,24-3,6y+y^2)+20(y^2-3,24)=50y^2+140,4\\\displaystyle \tt 97,2-108y+30y^2+20y^2-64,8=50y^2+140,4\\\displaystyle \tt 32,4-108y+50y^2=50y^2+140,4\\\displaystyle \tt -108y+50y^2-50y^2=140,4-32,4\\\displaystyle \tt -108y=108\\\displaystyle \tt y=108\div(-108)\\\displaystyle \tt \bold{y=-1}$