Can you please explain to me what is the execution time T(n) of the 3 algorithms?

Algorithm 1:

y ← 0
j ← n
while j >= 1 do {
k ← 0
while k < n*n do {
y ← y + j - k
k ← k + 1
}
j ← j - 1
}
return y

Algorithm 2:

for i ← 1...