x^2 - 10x + 25 = 35
x^2 - 10x + 25 - 35 = 0
x^2 - 10x - 10 = 0
[tex]x = \frac{-(-10) \pm \sqrt{(-10)^2-(4 \times1 \times -10)}}{2 \times 1} \\ = \frac{10 \pm\sqrt{100+40}}{2}= \frac{10 \pm \sqrt{140}}{2} \\ = \frac{10 \pm 2 \sqrt{35}}{2}=5 \pm \sqrt{35}[/tex]
