Wah..I need to ask my bro to answer this.. Brb
Answer:
See below
Step-by-step explanation:
We want to prove that

Taking the RHS, note

Remember that

Therefore,

Once

Then,

Hence, it is proved
Answer:
Step-by-step explanation:
To put the equation into vertex form, we need to complete the square

This is in the form

So, the vertex is (2, -5)
and 
Answer:
B
Step-by-step explanation:
Think of it like a quarter you got a half and half shot if getting heads or tails. meaning a 50/50 chance.