Answer:
r = -1
Explanation:
This is the answer because:
1) You can take the root of both sides and solve
2) You can also isolate the variable and solve for it
1. r9 + 1 = 0, divide 9 and 0 first. 9 x 0 = 0
2. r + 1 = 0, subtract 0 and 1. 0 - 1 = -1
Hope this helps!