>>10397478If d = 0, e ? 0: y2(x) = ex + f => x = (y2(x) - f)/e
Insert this into y1(x).
If d ? 0, with e' = e/d, f' = f/d:
y2(x)/d = x^2 + e'x + f' = (x + e'/2)^2 - e'/4 + f'
x = sqrt(y2(x)/d + e'/4 - f') - e'/2 (too lazy to check the bounds)
Insert this into y1(x).
