Question

Which of the following are the coordinates of the vertex of y=-x^2+2x+1

Answer 1

y=-x²+2x+1
way 1:
common equation of parabola is y=ax²+bx+c.
rule: x₀=-b/(2a), y₀=-D/(4a), where x₀ and y₀ are coordinates of the vertex.
According to the described rule above x₀=(-2)/(-2)=1, y₀=8/4=2.
The vertex is (1;2).
way 2:
re-write the given equation into the form y=(x+m)²+n.
y=-(x-1)²+2.
Rule: point (-m;n) is vertex of the parabola.
According to the described rule the vertex is (1;2).