You need to brush up on your Factoring . . .
1. Factor the trinomial: .
We have: .2. Solve: .
I assume you can finish this problem now . . .
We have: .3. Solve: .
Factor: . . . . etc.
then you'll have ax^2-bx+c
then you can use the quadratic equation:
x= (-b +/- ((-b)^2 -4ac)^1/2))/2a
here is a nicer version of the formula:
and then you just sub in the number and you'll get an answer
(sorry i'm new, and maybe not the best person at explaining)
EDIT: this works for numbers 2 and 3, although i think that Soroban's method is a lot easier :P