|
Question 284904: Trying to find max y-value of the graph y=2x^2+4x+1
Answer by nyc_function(2741)   (Show Source):
You can put this solution on YOUR website! The maximum y-value is the y-coordinate of the vertex.
Find the vertex in the form (x,y) and then write down the y-value.
Can you take it from here?
Do you know how to find the vertex?
===================================
You stated:
"No, I don't understand how to find the vertex if I am not given any points for "a" or "b" (since I'm supposed to use x = -(b/2a), right?)"
===================================
The first thing to do is find the x value using -b/2a as you said.
Let a = 2, b = 4 from your function.
x = -b/2a
x = -4/2(2)
x = -4/4
x = -1....This is the x coordinate (x-value) of the vertex. We can now find the y-value (also called y coordinate) by replacing every x you see in your function with -1 and doing the math.
y = 2x^2+4x+1
Let x = -1
y = 2(-1)^2 + 4(-1) + 1
y = 2 - 4 + 1
y = -2 + 1
y = -1
The y-value is, in this case, the same as the x-value, which is -1.
The maximum y-value is -1.
By the way, this is a parabola that opens upward (looks like a big letter U) with vertex at the point (-1,-1).
Got it?
|
|
|
| |
