What is the value of the greater root of the equation x² - 7x - 30 = 0?

Question: What is the value of the greater root of the equation x² - 7x - 30 = 0?

Solution:
x² - 7x - 30 = 0
⇒ x ² - 10x + 3x - 30 = 0
⇒ x(x - 10) + 3(x - 10) = 0
⇒ (x - 10)(x + 3) = 0

so the roots of the equation are x₁ = 10 and x₂ = - 3

So the greater one is obviously 10.