Answer:256
Step-by-step explanation:
do 
which equals 
so your answer would be 256
mark me as brainliest pls :)
The process is:
C = 2nr
2nr = c
r (2n) = c

That's the answer☝️☝️☝️☝️
or maybe this one
r = 2n + c
sorry, I'm unsure, it has been too long since I studied that...
Answer:1,4/5
Step-by-step explanation:https://www.cymath.com/answer?q=5x%5E2%2Bx%3D4