Question

Help me plz someone!

Answer 1

y = -2x² + 8x - 20

y = ax² + bx + c, a = -2, b = 8, c = -20

Line of symmetry is given by:

x = -b/2a x = -8/(2*-2) = -8/-4 = 2

x = 2

Vertex is the corresponding point.

y = -2x² + 8x - 20, x = 2

y = -2*(2)² + 8*2 - 20 = -2 *4 + 16 - 20 = -8 + 16 -20 = -12

So vertex is x = 2 and y = -12, that is (2, -12)

Vertex is (2, -12) and axis of symmetry, x = 2

Option D.

Hope this helps.

Answer 2

So in this equatin
a= -2
b= 8
c= -20

We can use the formula -b/2a to find the x coordinate of the vertex
-8/-4 = +2

There are only two choices that have 2 as x. Those are A and D.
Now we know that the axis of symmetry should be the same as the x coordinate of the equation, so the axis of symm. is equal to x=2
That makes the answer D