Question

How do you solve `9a=-a²-18`?

Answer 1

`a=-3`, and `a=-6`.

Explanation:

Start bringing everything on the same side changing the sing when you "jump" the `=` symbol.

`a^2+9a+18=0`

Now you can use the formula for the second order equation

`a=(-9\pmsqrt(81-4*18))/2=(-9\pmsqrt(9))/2=(-9\pm3)/2`.
The solution with the `+` is
`a=-3`
and the solution with the `-` is
`a=-6`.