This is not easy ...
First you have to write it as an equation = 0:
x^2-2x-35 = 0.
Then, find the roots with he quadratic formula:
x = (2 +/- sqrt(4 + 280))/2, sqrt(284) = 16.85 ...
Uh, so now with roots:
sqrt(284) = sqrt( 4*71) = 2*sqrt(71), sounds too difficult for an online question ...
Let's move on:
roots = 1+/- sqrt(71), so
x^2 - 2*x -35 = (x - 1 - sqrt(71))*(x - 1 + sqrt(71))
You have to try values less, in between or greater than the roots. GOing straight to the point,
(-infinity, 1 - sqrt(71) ) And ( 1 + sqrt(71), infinity)