Question

The line of symmetry for the quadratic equation y = ax2 - 8x - 3 is x = 2. What is the value of \"a\"?. -2. -1. 3

Answer 1

The value of a is 2

Explanation:

The quadratic equation is
`y=ax^2-8x-3`

The line of symmetry is x =2.

We know that the graph of quadratic function is a parabola and the line of symmetry of a parabola always passes through the vertex.

The line of symmetry is x =2.

And the x-coordinate of the vertex is
`-(b)/(2a)`

Hence, we have

`2=-(-8)/(2a)\\\\4a=8\\\\a=2`

Thus, the value of a is 2

Answer 2

Formula for the axis of symmetry ( or x-coordinate of the vertex ):
x = -b / 2a
2 = -(-8) /2 a
2 = 8 / 2a
2 a = 4
Answer: a = 2