The 4th term of the sequence can be determined as,

Thus, option (b) is correct.
A) if the diameter is 13 the radius is 6.5

b)if the diameter is 6 the radius will be 3

hope this helps
Y= -35
Y = -1
I put the work in the picture below!
(Hint: just substitute the x for its number and do simple adding and subtracting)
Rational. Irrational are numbers that cannot be written as fractions. 8 can be written as a fraction. 8/1