Solve the simultaneous equations y + 4x + 1 = 0 and y^2 + 5x^2 + 2x = 0

y=-4x-1
(-4x-1)^2 +5x^2 +2x=0

16x^2 +8x +1 +5x^2 +2x=0

21x^2 +10x + 1 =0
(7x+1)(3x+1)=0

x=-1/7 or -1/3

y= -3/7 or 1/3