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5 votes
Axis of symmetry and vertex of F (x) = x2 + 4x -5

User MarisP
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2 Answers

7 votes
r= -b/2a = -4/2=-2 k=f(r)=-2^2-8-5=-9 (-2,-9)
User Ziffusion
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9.0k points
4 votes
axis of symmetry is also the x coordinate of the vertex
if you have
f(x)=ax^2+bx+c
vertex x coordinate is
-b/2a
a=1
b=4
-4/2(1)=-4/2=-2
x coordinate of vertex=-2 aka axis of symmmetry
find y coordinate
input -2 for x
y=(-2)^2+4(-2)-5
y=4-8-5
y=-9

axis of symmetry is x=-2
vertex is (-2,-9)
User Fernando Carvajal
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8.5k points