SOLUTION: Can someone please help me solve this equation? Thank You!!!! Find the maximum Y-value on the graph of Y=f(x) F(x)=-x^2+10x+9 The maximum Y-value is Y=____ It does not show

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Can someone please help me solve this equation? Thank You!!!! Find the maximum Y-value on the graph of Y=f(x) F(x)=-x^2+10x+9 The maximum Y-value is Y=____ It does not show       Log On


   

Question 762753: Can someone please help me solve this equation? Thank You!!!!
Find the maximum Y-value on the graph of Y=f(x)
F(x)=-x^2+10x+9
The maximum Y-value is Y=____
It does not show a graph on the equation so I have no idea what to do with this equation?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Use the formula x = -b/(2a) to find the x coordinate of the vertex

x = -b/(2a)

x = -10/(2*(-1))

x = -10/(-2)

x = 5


The x coordinate of the vertex is at x = 5

Plug it in to find the max y value

f(x) = -x^2+10x+9

f(5) = -(5)^2+10(5)+9

f(5) = -25+10(5)+9

f(5) = -25+50+9

f(5) = 25+9

f(5) = 34

So the maximum y value is y = 34