Please factor this equation?

You can take the 4 out first:
4*[r^2 -r -10]

You need to find two numbers whose product is -10 and whose sum is -1, what to we have to choose from (ignoring signs)?
(1,10) and (2,5), no whole number works.

Lets use the quadratic equation to see if I made a mistake on choices: r = 1 +/- sqrt(1 - 4*1*10)/2, well only complex solutions left so the only thing we can do is just factor out the 4.

You really need to learn to factor yourself. You'll need it for every math from middle school until you're done with school.

4(r^2-r-10)

R= [1+(41^0.5)]/2 and [1-(41^0.5)]/2