Answer:
x1=3. x2=-2
Step-by-step explanation:

b=-1
a=1
c=-6





x1=3
x2=-2

Use the formula i=prt, where i is the interest earned, p is the principal, r is the rate (as a decimal fraction) and t is the elapsed time, in years.
Here i = $72 = $1200 r (9/12) (9 months is 9/12, or 3/4, of 1 year)
Reducing,
$72 = $900r
Solving for r, r=0.08, or 8 percent per year.
The answer is (1,4) and (-1,-4)
I believe that 21 is d 27 over 17
I believe that 22 is d because 16 divided by 3.20 is 5
sorry if I am wrong
I hope this helps you