halp meh

1. Guest was almost right, but he/she forgot to multiply by 2 when squaring the binomial. So the answer is 12.

2. $(r-s)^2 = r^2-2rs+s^2$. By Vieta's formulas, $r+s = \frac{-6}{-1} = 6$, and $rs = \frac{2}{1} = 2$ so $(r+s)^2= r^2+2rs+s^2 = 6^2=36$. Now just subtract $4rs=8$ from 36 to get what we want, so the final answer is 28. 

3. Divide $3x^2-4x+15=0$ by 3 to get $x^2 - \frac{4}{3}x + 5 = 0$. Therefore, the ordered pair is $(\frac{-4}{3}, 5)$

1.  If  2x^2  + bx + 18  =  0   has a double root......then the discriminant   =  0 

So

b^2  - 4 * 2 * 18  = 0

b^2  -  144   = 0

b^2   = 144

b  =12   or  b =  -12