Write each polynomial in ascending powers of $\mathbf{x}$. $1.26-3 x+5 x^{3}+1+x^{2}$

Step 1 ：1. Combine like terms: \(1.26 - 3x + 5x^3 + 1 + x^2 = 2.26 - 3x + x^2 + 5x^3\)

Step 2 ：2. Arrange the terms in ascending powers of x: \(\boxed{2.26 - 3x + x^2 + 5x^3}\)