3. The chord $A B$ of the parabola $y=x^{2}$ intersects the y-axis at point $C$ and is divided by it in the ratio $A C: C B=5: 3$. Find the abscissas of points $A$ and $B$, if the ordinate of point $C$ is 15.
Answer: $\left(x_{A}=-5, x_{B}=3\right),\left(x_{A}=5, x_{B}=-3\right)$.