Which value of a would not make the following expression completely factored? x² - a 
12, 36, 49, 81

Solution:

In order to make an expression completely factored,it must have roots that satisfy that expression

So, the expression should be equal to zero

x² - a = 0

x² = a

x = √a

Here, a must be positive and a perfect square.

From the options given, only 12 is not a perfect square, 36/49/81 are perfect squares.

Hence a = 12 would not make the expression completely factored.

Which value of a would not make the following expression completely factored? x² - a 

Summary:

The value of a = 12 would not make the following expression completely factored x² - a.