import torchdef f(x):    return x**4 + 3*x**2 + 2*xx = torch.tensor([2.0], requires_grad=True)y = f(x)y.backward()print(f"f(2) = {y.item()}, f'(2) = {x.grad.item()}")# Output: f(2) = 42.0, f'(2) = 58.0