Which binomial is a factor of the quadratic trinomial x2 − 7x + 12?

How do i do this? i don’t understand

Given that y varies directly to the square root of (x + 1), and that y = 1 when x = 8,(a)express y in terms of .x,(b)find the value of y when x = 3,(c)find the value of x when y = 5.

Factor the polynomial expression x6 – x3 – 20