2х^2-2х+х-1-(2х^2-х+2х-1)=24
2x^2-2x+x-1-2x^2+x-2x+1=24
-2x=24
x=-12
3^2n+3^2n-2/(3^2)^n-1 = 3^2n+3^2n-2/3^2n-2= 3^2n-2-2n+2=3^2n+3
(6а-в)(а-в)-3(а-в)(а+в)=6а^2-6ав-ав+в^2 - 3(а^2-в^2)= 6а^2-7ав+в^2 - 3а^2+3в^2= 3а^2-7ав+4в^2
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