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(3а-1)(3а+1)-(3а-1)^2= 9a^2 +3a-3a-1-9a^-1+6a=6a-2.
2х-12х-5х-30+6х-4=(10х+5)2+11
13х-34=100х+25+11
100х-13х=25+11-34
87х=2
х=43,5
2xy² * 0,25x²y⁵ = 0,5x¹⁺²y²⁺⁵ = 0,5x³y⁷
4х-8-2х+3=0
2х-5=0
2х=5
х=2,5