Question

The axis of symmetry for the graph of the function is f(x)=1/4x2+bc+10 is x=6. What is the value of b?

Answer 1

for
`f(x)=ax^2+bx+c`, the axis of symmetry is
`x=(-b)/(2a)`

given that axis of symmetry is x=6,
`(-b)/(2a)=6`

we know that a=1/4 from the problem, so

`6=(-b)/(2((1)/(4)))`

`6=(-b)/((1)/(2))`

`6=-2b`

divide by -2 both sides

`-3=b`

the value of b is -3