Answer:
c) (3-7x^2)(x-3)
Step-by-step explanation:
-7x^3+21x^2+3x-9
Factor out a -7x^2 from the first two terms and a 3 from the last two terms
-7x^2 (x -3) +3(x-3)
Now factor out (x-3)
(x-3) (-7x^2+3)
Rearranging)
(x-3) (3-7x^2)
Any

in this set will be real numbers that are both less than

and greater than

. But that's not possible, so this set is empty.
B and d should be the answer
Well first turn 1/7 and 1/5 into decimals which would be .142857 and .2 Add those to 7 and 5 to get 7.143 (I rounded this to the nearest thousandth) and 5.2 Divide those and you get 1.374
V= pi x r^2 x h
V/(pi x h)=r^2
square root of [V/(pixh)]=r