Thread: 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...

Let's take a look at the equation you gave:



To find the y-intercept you set in the equation and this will give you the y co-ordinate of the point where f(x) crosses the y-axis.

so i.e. crosses the y-axis at the point (0,10).

To find the x-intercept you set , i.e.



The easiest way to do this is to factorise:


or
(If factorising doesn't work use the quadratic formula .)

So crosses the x-axis at the points (2,0) and (5,0).