Question

Choose the equation below whose axis of symmetry is x = 0.

y = x2 + 2x
y = x2 − 16x + 58
y = x2 + 2
y = x2 − 4x + 2

Answer 1

@welshfella @ganeshie8

Answer 2

Ok, so I change all Y to 0.

Answer 3

oh sorry
x = 0 is the y axis

Answer 4

Ok. Make x = 0. What do I do after that?

Answer 5

so you need to chooses a function which will give you 2 values +/- a for one value of y.

Answer 6

I thought it was x = -b/2a

Answer 7

In my opinion it is easier to just know the translations of these types of graphs. They all move up and down or side to side in the same way if you know how to "read" the equation.

Answer 8

yeah - that another way of attempting a solution . b/2a will give you the axis of symmetry for a parabola

Answer 9

So is the value for C 2?

Answer 10

yes @IMStuck

Answer 11

No

Answer 12

try looking at the transformations of the graphs

Hint: what does the graph of y = x^2 look like?

Answer 13

http://prntscr.com/c1zowp

Answer 14

right What is that symmetrical about/

Answer 15

it splits it down the middle at the 0

Answer 16

yes so its symmetrical about x = 0 ( that is the y-axis)

Answer 17

And y = x^2 + 2 is same shaped graph moved 2 units up the y axis.

Answer 18

so C is your answer

Answer 19

applying the -b/2a thing to 2x^2 + 2 you need to write it in the form
y = 2x^2 + 0x + 2

so -b/2a = 0/ 4 = 0

so the axis of sym is x = 0