Answer :

pepe11
What do you mean, "solve"?
y = -4(x-2)² + 4 
the line is a parabol with a maximum (2;4)
it's roots are  -4(x-2)² + 4  = 0 => (x-2)² = 1 => x-2 = 1 => x = 3
                                                              => x-2 = -1 => x = 1 
symetrical axe: x = 2
is that all you need?

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