Question

Help pls

What is the line of symmetry for the parabola whose equation is y = -x^2 + x + 3?

The line of symmetry for the quadratic equation y = ax^2 + 8x - 3 is x = 4. What is the value of "a"?

Find the vertex of the parabola whose equation is y = x^2 + 6x + 2.

What is the line of symmetry for the parabola whose equation is y = 3x^2 + 24x - 1?

What is the line of symmetry for the parabola whose equation is y = x^2 + 10x + 25?

Find the vertex of the parabola whose equation is y = -2x^2 + 8x - 5.

What is the line of symmetry for the parabola whose equation is y = x^2

Answer 1

whoa nellie
how many questions you got? lets do the first one

Answer 2

this is 7 out of 10 that i got wrong on a test i have for an online class :'[

Answer 3

line of symmetry of \(y=ax^2+bx+c\) is \(x=-\frac{b}{2a}\)
line of symmetry for \(y=-x^2+x+3\) is \(x=\frac{-1}{2\times (-1)}=\frac{1}{2}\)

Answer 4

first one is therefore \(x=\frac{1}{2}\)

Answer 5

thank you @satellite73

Answer 6

want to try the next one?

Answer 7

i dont know what to do with a and x

Answer 8

\[ y = ax^2 + 8x - 3 \]
you don't do anything with the \(x\)
you are told that the axis of symmetry is \(x=4\) making \(-\frac{b}{2a}=4\)

Answer 9

since \(b=8\) you have
\[-\frac{8}{2a}=4\] and you can solve that equation for \(a\)

Answer 10

there isnt a b there..

Answer 11

whoa lets back up
general form is
\[\large y=\color{red}ax^2+\color{blue}bx+\color{green}c\]
you have
\[\large y=\color{red}ax^2+\color{blue}8x+\color{green}{-3}\]

Answer 12

that makes \(\color{blue}b=\color{blue}8\)

Answer 13

oh i see

Answer 14

is a 1?

Answer 15

now your job is to solve
\[-\frac{8}{2a}=4\] for \(a\)

Answer 16

not quite
don't forget the \(-\) sign

Answer 17

no wait i got it a is -2

Answer 18

-1*

Answer 19

\[-\frac{8}{2a}=4\\
-8=8a\\
-1=a\]

Answer 20

right

Answer 21

i meant to put 1

Answer 22

k good

Answer 23

thanks! @satellite73

Answer 24

there is this really cool program called geogebra, you can type equations in and it will graph, it helped me a lot with these types of problems,

Answer 25

post the next one in a new thread and i will help you with it