Answer:
The number is 9.
Step-by-step explanation:
I've no idea how to show your work on this one, but here's my thought process:
I know that 81 is 9², and that their sum is 90.
Answer:
-10 or 9
Step-by-step explanation:
Lets set it up like an equation
x + x^2 = 90
x^2 + x -90 = 0
Use abc-formula
to find x = -10 or 9
We put this into the original equation and find that both answers fit the equation
