Hi, I'm new to Math Help Forum and was wondering if you could help me with functions and finding the x-intercepts and the coordinates of the vertex.

I'm having a hard time with these questions:

y=x^2+7x

and

y= 15x^2+16-7

Can you please explain step by step. I use the quadratic formula but my anwser seems be be wrong.

thanks for taking time to read this, hopefully you can help.