Answer:
see explanation
Explanation:
given a quadratic in standard form
y = ax² + bx + c (a ≠ 0 )
• if a > o then curve opens up
• if a < 0 then curve opens down
for y = - 2x² + 4x ← in standard form with a = - 2, b = 4 and c = 0
here a = - 2 < 0 so curve opens down
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the axis of symmetry is a vertical line passing through the vertex
the x- coordinate of the vertex, which is also the equation of the axis of symmetry is
x = -
= -
= 1
equation of axis of symmetry is x = 1
substitute x = 1 into the equation for y- coordinate of vertex
y = - 2(1)² + 4(1) = - 2 + 4 = 2
vertex = (1, 2 )
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to find the zeros let y = o , that is
- 2x² + 4x = 0 ← factor out - 2x from each term
- 2x(x - 2) = 0
equate each factor to zero and solve for x
- 2x = 0 ⇒ x = 0
x - 2 = 0 ⇒ x = 2
the zeros are x = 0 and x = 2
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since the graph opens down then it has a maximum value
this is the y- coordinate of the vertex
thus maximum at y = 2