Question

1) -у*(у+7)=(2+у)-(у-2)

2) (3у-1)*(у+3)=у (6у+1)

3) (у+1)*(у-1)=2 (5у+10,5)
решите

Answer 1

$1)-y(y+7)=(2+y)-(y-2)\\-y^2-7y=2y-y+2\\y^2+7y+4=0\\D=49-16=33\\y_1=\frac{-7+\sqrt{33} }{2} \\y_2=\frac{-7-\sqrt{33} }{2}\\2)(3y-1)(y+3)=x(6y+1)''3y^2+9y-y-3=6y^2+y\\3y^2-7y+3=0\\D=49-46=13\\y_1=\frac{-7+\sqrt{13} }{6}\\y_2=\frac{-7-\sqrt{13} }{6}\\3)(y+1)(y-1)=2(5y+10,5)\\y^2-1=10y+21\\y^2-10y-22=0\\D_1=25+22=47\\y_1=5+\sqrt{47} \\y_2=5-\sqrt{47}$