Find the equation of the axis of symmetry and the coordinates of the vertex of the graph of the following function

y=-3x^2+4x-5

Question

Find the equation of the axis of symmetry and the coordinates of the vertex of the graph of the following function

y=-3x^2+4x-5

welshfella · Answer

you need to convert this to the form a(x - b)^2 + c  where the axis of symmetry is x = b

welshfella · Answer

-3x^2 + 4x - 5
divide through by -3:-
= -3(x^2 - (4/3) x +5/3)
=  -3((x - (2/3 )^2 - 16/9 + 5/3)
can you see what the axis of symmetry is ?
- compare it with the general form in my first post

welshfella · Answer

look where b is  and what is in the same place in the last line of my working

welshfella · Answer

going from x^2 - (4/3) x  to (x - (2/3) x )^2 -16/9  is called completing the square

anonymous · Answer

so the axis of symmetry would be 2/3

welshfella · Answer

x = 2/3   yes