Hope this is straightforward.
Answer:
(y+b)/a = x
Step-by-step explanation:
y = ax − b
Add b to each side
y+b = ax − b+b
y+b =ax
Divide each side by a
(y+b)/a = ax/a
(y+b)/a = x
256 = 16^2. In turn, 16=4^2.
The 4th roots are {4, 4, -4 and -4}.
Check for yourself: Does 4^4= 256? does (-4)^4 = 256?