Find all the values of the parameter 'a' for which the inequality `4^x-a2^x-a+3 <= 0` is satisfied by at least one real x.

Explanation

To solve the inequality \( 4^x - a \cdot 2^x - a + 3 \leq 0 \) for the parameter \( a \), we will follow these steps:

### Step 1: Rewrite the inequality
We start by rewriting \( 4^x \) as \( (2^2)^x = (2^x)^2 \). Let \( t = 2^x \). Thus, we can rewrite the inequality as:
\[ t^2 - a t - (a - 3) \leq 0 \]

...