hi,

i'm doing a question on cubic graphs and i was told that if there is a squared value involved the graph line will touch rather than cross directly the x axis. i've come to a question that is

so i thought it may touch because it has a square value then realised it doesn't when i looked at the answer. so i thought maybe i should factorise the quadratic equation but i don't think you can? what has gone wrong here?

thanks, mark

ah i've just realised the quadratic formula might need to be used, any input would still be appreciated though