Answer:
-4.33333333333
Step-by-step explanation:
We have the equation:

We know two points and we will use them to calculate the parameters a and b.
The point (0,3) will let us know a, as b^0=1.

Now, we use the point (2, 108/25) to calcualte b:
![\begin{gathered} y=3\cdot b^x \\ \frac{108}{25}=3\cdot b^2 \\ 3\cdot b^2=\frac{108}{25} \\ b^2=\frac{108}{25\cdot3}=\frac{108}{3}\cdot\frac{1}{25}=\frac{36}{25} \\ b=\sqrt[]{\frac{36}{25}} \\ b=\frac{\sqrt[]{36}}{\sqrt[]{25}} \\ b=\frac{6}{5} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20y%3D3%5Ccdot%20b%5Ex%20%5C%5C%20%5Cfrac%7B108%7D%7B25%7D%3D3%5Ccdot%20b%5E2%20%5C%5C%203%5Ccdot%20b%5E2%3D%5Cfrac%7B108%7D%7B25%7D%20%5C%5C%20b%5E2%3D%5Cfrac%7B108%7D%7B25%5Ccdot3%7D%3D%5Cfrac%7B108%7D%7B3%7D%5Ccdot%5Cfrac%7B1%7D%7B25%7D%3D%5Cfrac%7B36%7D%7B25%7D%20%5C%5C%20b%3D%5Csqrt%5B%5D%7B%5Cfrac%7B36%7D%7B25%7D%7D%20%5C%5C%20b%3D%5Cfrac%7B%5Csqrt%5B%5D%7B36%7D%7D%7B%5Csqrt%5B%5D%7B25%7D%7D%20%5C%5C%20b%3D%5Cfrac%7B6%7D%7B5%7D%20%5Cend%7Bgathered%7D)
Then, we can write the equation as:
Answer:
11 is 405, 12 is 107.5, 13 im not sure of
Step-by-step explanation:
First on 11 you can just do 21*21 (the big square) and subtract that by 36 (which is 6*6, the small square), you'll get 107.5.
Then on 12, it is made up of a large rectangle, a small triangle, and a flatter triangle. The top triangle's formula is 1/2(7*3) which = 10.5. The big rectangle is 13*7 = 91. The last triangle is 1/2(4*3) which = 6. It is 3 because 13-10. Add all those up and you should get 107.5.
And I just want to know on number 13 if that 11 is the radius or diameter. I can't seem to tell.