Answer:
Step-by-step explanation:
1). x² - 10x + a²
By using the formula of (a - b)² = a² - 2ab + b²
x² - 2(5)x + a²
Therefore, for a perfect square of the expression a should be equal to 5.
Therefore, (x² - 10x + 25) will be the answer.
2). x² + 2ax + 36
= x² + 2(a)x + 6²
For a perfect square of the given expression value of a should be 6.
x² + 2(a)x + 6² = x² + 2(6)x + 6²
= (x + 6)²
Therefore, x² + 12x + 36 will be the answer.
3). 

To make this expression a perfect square,
a² = 
= 
Therefore, the missing number will be
.
Identities have <em>INFINITE </em>solutions.
Hope I could help! :)
I'm sure you already know the axis which is x= -2. The vertex is (-2,-9). You can use the graph or solve to find the vertex. I hope this helpful.