Question

Решить систему уравнений x-5y=3 x²-2xy-y²=-1

Answer 1

x-5y=3

x=5y+3

x²-2xy-y²=-1

(5y+3)²-2(5y+3)y-y²=-1

(25y²+2*5y*3+9)-(10y²+6y)-y²=-1

25y²+30y+9-10y²-6y-y²=-1

14y²+24y+10=0

7y²+12y+5=0

(7y+5)(y+1)=0

y = -1  или y = -5/7

x=5y+3

x= -2 или х =5*( -5/7) + 3 = -25/7 + 3 = - 4/7