ANSWER
The vertex of the graph of

is

EXPLANATION
The vertex form of a parabola is given by

where

is the vertex of the parabola.
The function given to us is

This is already in the vertex form.
When we compare this to the general vertex form, we have,


and

Therefore the vertex of the parabola is

Hence the correct answer is option A.
I won't answer them all for you (don't want to cheat - need to learn something).
But for the first one given:
<span>-2x-9y=-25
-4x-9y=-23
you set up either x or y (which ever one you want to eliminate) so that one of them cancels.
So this one is easy - you just have to multiply an entire row by negative (doesn't matter which one) - so that the y's will be + and -
Since they're both 9 and they're subracting NOW - you can eliminate the y value. Now add/subtract the x's. So it'd be -2 or 2 depending on how you eliminated y. Then add the number outside of the = sign. Now just solve for x. After that plug in whatever you got for x into both of the rows. Then find the y value.
Hopefully this wasn't confusing -- reply if it is and I will try to simplify. I can give you contact if you need help with the rest
Good luck!</span>
5x - 20 = 8x - 65
-20 = 3x - 65
3x = 45
x = 15
The gardener will need to buy 60 feet of fencing. Because the square root of 225 if 15, and 15 times 4 is 60. So, 60 is the perimeter of the garden.