Blue graph (on the left):

ais the horizontal axis,bis the vertical axis.Green graph (on the right:

xis the horizontal axis,yis the vertical axis.

y = -x^2 - b * x + a | |

y = -x^2 + 5 * x - 6 | y = x^2 - 14 * x + 48 |

y = x^2 + 14 * x + 48 | y = x^2 + x - 2 |

y = -x^2 + 11 * x - 28 | y = -x^2 - 8 * x - 15 |