Question

The line of symmetry for the quadratic equation y = ax2 + 8x - 3 is x = 4. What is the value of "a"?

-2
-1
1

Answer 1

`y=ax^2+8x-3 \\ a \\ b=8 \\ \\ \hbox{the line of symmetry: } x=4`

The equation of the line of symmetry of a parabola is
`x=-(b)/(2a)`.


`-(8)/(2a)=4 \ \ \ |* 2a \\ -8=8a \ \ \ |/ 8 \\ a=-1`

The value of a is -1.