Answer:
![a=-(1)/(8)](https://img.qammunity.org/2022/formulas/mathematics/high-school/epvvtfyuble1jzokcgk5oo41etudc5oqfh.png)
Explanation:
Given
See attachment for graph
Required
Write the vertex form and then solve for
The general equation is:
![y = a(x - h)^2 + k](https://img.qammunity.org/2022/formulas/mathematics/college/a4ohmj341p6jyoe737jwo7mmb8yxfwproc.png)
From the attachment, the vertex is at:
![(h,k) = (24,50)](https://img.qammunity.org/2022/formulas/mathematics/high-school/tpzbi0sofmu2b2v9l2nkpwvzt6542eojx4.png)
i.e.
![h = 24; k= 50](https://img.qammunity.org/2022/formulas/mathematics/high-school/47pix62sck34grvn1zk3j7eg25bts8r4fi.png)
Considering point:
![(x,y) = (4,0)](https://img.qammunity.org/2022/formulas/mathematics/high-school/wk0xfr0mkzszwpbxlgs1gky384bzb9f2jz.png)
i.e.
![x=4;y=0](https://img.qammunity.org/2022/formulas/mathematics/high-school/8saa5i2a6qd5o69r572duzqs8bi691l6sr.png)
Substitute these values in
![y = a(x - h)^2 + k](https://img.qammunity.org/2022/formulas/mathematics/college/a4ohmj341p6jyoe737jwo7mmb8yxfwproc.png)
![0 = a(4 - 24)^2 + 50](https://img.qammunity.org/2022/formulas/mathematics/high-school/2wc2rjly0q4i2due0xc1xz9rkoxsnhb8c3.png)
![0 = a(- 20)^2 + 50](https://img.qammunity.org/2022/formulas/mathematics/high-school/4rcyvr666tszvhn4wrkxngxf5k3lb7xapk.png)
![0 =a(400) + 50](https://img.qammunity.org/2022/formulas/mathematics/high-school/lkmnetguz54uqi4c4ndyunknbk31gyr5jz.png)
![0 = 400a + 50](https://img.qammunity.org/2022/formulas/mathematics/high-school/p7k4eqas8kiacdddeoz76wmr8aof1f8jt1.png)
Solve for a
![400a = -50](https://img.qammunity.org/2022/formulas/mathematics/high-school/wqwjv8a04k7t24l5qbc3lsq0m49whddyi4.png)
Make a the subject
![a=-(50)/(400)](https://img.qammunity.org/2022/formulas/mathematics/high-school/h9evp0vi82ujjw9w9scjwshddccdr2z19n.png)
![a=-(1)/(8)](https://img.qammunity.org/2022/formulas/mathematics/high-school/epvvtfyuble1jzokcgk5oo41etudc5oqfh.png)