Ok, my teacher isnt a very good one because he expects us to know this kind of math. I am a 14 year old sophomore and I'm in a class full of senoirs and junoirs who have had Pre-ap algebra 2 the year before and failed it and they are retaknig it. the f(x)=5x squared+x8-7. only the first x variable is squared but i have no clue how to get to the reverse answer. the answer is .4 but i dont know how to get there. help? please?