How do you find the x-intercepts of Quadratic functions?

I've been Googling quadratic functions on how to to find the x-intercepts, I did find the instructions, but they're like "do this so this would equal this, etc" and they aren't really explaining how to do it... I have a test soon so I want to be able to know how to find the x-intercepts of quadratic functions in an easy way.

One of my problems is** f(x)= x^2 -7x+10**

Can someone tell me how to do these kinds of problems step by step?

Another problem that is different from this is f(x)=x^2 -9x...