What is the vertex of the graph of y + 2x + 3 = -(x + 2)2 + 1?
(-3,-33); (-3,3); (3,-24); (3,21)
Solution:
y + 2x + 3 = -(x + 2)2 + 1 [Given]
The vertex of the parabola, which is denoted as the coordinates (h, k).
The standard equation of the parabola is y = a(x-h)2 + k
The given equation can be written as
y = -(x + 2)2 + 1 - 2x - 3
Expand using the algebraic identity (a + b)2 = a2 + b2 + 2ab
y = - (x2 + 4 + 4x) + 1 - 2x - 3
y = -x2 - 4 - 4x - 2x - 2
By further calculation
y = - x2 - 6x - 6
Taking negative sign common in the first two terms
y = - (x2 + 6x) - 6
Now add and subtract 9 on the RHS using completing the square.
y = - (x2 + 6x + 9 - 9) - 6
So we get
y = - (x + 3)2 + 3
y = - (x - (-3))2 + 3
Vertex = (-3, 3)
Therefore, the vertex of the graph is (-3, 3).
What is the vertex of the graph of y + 2x + 3 = -(x + 2)2 + 1?
(-3,-33); (-3,3); (3,-24); (3,21)
Summary:
The vertex of the graph of y + 2x + 3 = -(x + 2)2 + 1 is (-3, 3).
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