Answer:

Explanation:
We are given:

And we want to solve this via completing the square.
First, we will subtract 3 from both sides. This yields:

Next, we will factor out the leading coefficient from the left.
In this case, the leading coefficient is simply 1 so we can leave it as is.
Next, we want to add a constant that is half of the b coefficient squared.
In this case, b = -5.
Half of that is -5/2.
Squaring yields 25/4.
So, we will add 25/4 to both sides. Since our leading coefficient is 1, we don't need to multiply by anything when we add it on the right. Hence:

The left side constitutes a perfect square trinomial as shown:

Factor and subtract:

Taking the square root of both sides gives:

Hence:

Approximate:
