13. Two parabolas param1 and param2 touch at a point lying on the Ox axis. A vertical line through point $D$ - the second intersection point of the first parabola with the Ox axis - intersects the second parabola at point $A$, and the common tangent to the parabolas at point $B$. Find the ratio $B D: A B$.

| param1 | param2 |  |
| :---: | :---: | :---: |
| $y=3 x^{2}+a x+b$ | $y=-2 x^{2}+c x+d$ |  |
| $y=7 x^{2}+a x+b$ | $y=-5 x^{2}+c x+d$ |  |
| $y=4 x^{2}+a x+b$ | $y=-x^{2}+c x+d$ |  |
| $y=5 x^{2}+a x+b$ | $y=-4 x^{2}+c x+d$ |  |
13. Two parabolas param1 and param2 touch at a point lying on the Ox axis. A vertical line through point $D$ - the second intersection point of the first parabola with the Ox axis - intersects the second parabola at point $A$, and the common tangent to the parabolas at point $B$. Find the ratio $B D: A B$.

| param1 | param2 | Answer |
| :---: | :---: | :---: |
| $y=3 x^{2}+a x+b$ | $y=-2 x^{2}+c x+d$ | 1.5 |
| $y=7 x^{2}+a x+b$ | $y=-5 x^{2}+c x+d$ | 1.4 |
| $y=4 x^{2}+a x+b$ | $y=-x^{2}+c x+d$ | 4 |
| $y=5 x^{2}+a x+b$ | $y=-4 x^{2}+c x+d$ | 1.25 |