why is x = 0 relevant here? greg uses this point to say that the 3x^2 + 4x option is wrong but since x=o is not a solution to the graph, I did not understand why it is used to deduce. help?
I think you meant root?
Hint: what is the value of 3x^2 + 4x when $x = 0? Can the value of the y-coordinate at x = 0 for the graph be 0?
That expression will be 0 unlike all the other expressions which will continue to have the value of the constant left behind even when the x-term is 0. So for x = 0, here y is necessarily 0. but I’m not able to relate that to the graph? sorry if I’m missing something obvious here. just not sure why we are looking at the origin or x = 0 when it does not intersect with the line (the bat signal).
The x-coordinate when y is 0 in the graph is definitely not 0 as it does not intersect the x-axis. You don’t necessarily know what the value is, but that does not matter.