Answer :

The formula [tex]\( c = \left(\frac{b}{2}\right)^2 \)[/tex] is used to complete the square in algebra.

Here is a detailed, step-by-step explanation:

1. Understanding "Completing the Square":
"Completing the square" is a method used in algebra to transform a quadratic expression of the form [tex]\( ax^2 + bx + c \)[/tex] into a perfect square trinomial. A perfect square trinomial is an expression that can be written as the square of a binomial.

2. Form of the Quadratic Expression:
Consider the quadratic expression [tex]\( x^2 + bx \)[/tex]. To complete the square, we need to transform it into the form [tex]\( (x + d)^2 \)[/tex], where [tex]\( d \)[/tex] is some number related to [tex]\( b \)[/tex].

3. Isolate the Terms:
Start with the expression [tex]\( x^2 + bx \)[/tex].

4. Determine the Value to Complete the Square:
To find the appropriate number to add and subtract (i.e., the value of [tex]\( c \)[/tex]), we use the formula [tex]\( c = \left(\frac{b}{2}\right)^2 \)[/tex]. This value of [tex]\( c \)[/tex] is what makes the expression a perfect square trinomial.

5. Applying the Formula:
Using the value obtained from [tex]\( c = \left(\frac{b}{2}\right)^2 \)[/tex]:
[tex]\[ x^2 + bx + \left(\frac{b}{2}\right)^2 \][/tex]
This trinomial can now be written as a perfect square:
[tex]\[ \left(x + \frac{b}{2}\right)^2 \][/tex]

6. Example:
For instance, if [tex]\( b = 6 \)[/tex]:
[tex]\[ c = \left(\frac{6}{2}\right)^2 = 3^2 = 9 \][/tex]
The original expression [tex]\( x^2 + 6x \)[/tex] can be transformed into:
[tex]\[ x^2 + 6x + 9 \][/tex]
Which can be written as:
[tex]\[ (x + 3)^2 \][/tex]

Thus, the formula [tex]\( c = \left(\frac{b}{2}\right)^2 \)[/tex] is used to complete the square in algebra by transforming a quadratic expression into a perfect square trinomial.

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