Use Euler's method to approximate the solutions for each of the following initial-value problems.
a. y' = y/t − (y/t)2, 1≤ t ≤ 2, y(1) = 1, with h = 0.1
b. y' = 1 + y/t + (y/t)2, 1≤ t ≤ 3, y(1) = 0, with h = 0.2
c. y' = −(y + 1)(y + 3), 0≤ t ≤ 2, y(0) = −2, with h = 0.2
d. y' = −5y + 5t2 + 2t, 0≤ t ≤ 1, y(0) = 1/3 , with h = 0.1