Final answer:
To complete the square in the given equation, add (6/2)² = 9 to both sides. The value of c that makes the second equation a perfect square trinomial is 9.
Step-by-step explanation:
To complete the square in the equation x² - 6x = 5, we need to add a constant term to both sides of the equation. The constant we add is half the coefficient of the x-term squared. In this case, the coefficient of the x-term is -6, so we add (6/2)² = 9 to both sides:
x² - 6x + 9 = 5 + 9
Now, we have a perfect square trinomial on the left side: (x - 3)² = 14. Therefore, the value of c that makes x² - 24x + c a perfect square trinomial is 9.