solve (5-b)^2 = y for b
1) Let's solve in ℝ: (5 -b)2 = y
A square being never negative, we need y ≥ 0; the two numbers whose square is y are then -y and y
5 -b = -y
ⓘ We subtract 5 from both sides
-b = -y -5
ⓘ We gather the terms in b on the right and the other terms on the left
y + 5 = b
Solution found: b = y + 5
5 -b = y
ⓘ We subtract 5 from both sides
-b = y -5
ⓘ We gather the terms in b on the right and the other terms on the left
-y + 5 = b
Solution found: b = 5 -y
2) Solving for y: y ≥ 0
Solution found: y ≥ 0
▶Solution:   { b = { 5 -y, y + 5 }, y ≥ 0 }