Anyone of you know how to do this question? the difference between the third term and second term of a geometric progression is three times the difference between the second term and the first term. (a)show that r^2-4r +3=0,where r is the common ratio (b)if the first term is 2,calculate the sum of the fourth and fifth terms

Part (a)the general term of a geometric progression with common ratio    is    the first term is  .the second and third terms are    the difference between the third term and the second term is    the difference between the second term and the first term is    and difference of third to second is three times difference of second to first.    divide both sides by      we have shown that  .======part (b)to get a value for r, we can take our equation from part (a) and factor it.two numbers that multiply to get +3 and add to get -4 are -3 and -1.    by zero factor property, the solutions are  . but solution  is extraneous because a geometric progression with a common ratio 1 is not of interest. so  .so this is a geometric progression with a first term of 2, common ratio of 3.the general term is therefore    fourth term:       fifth term:       the sum of the two terms is 54 + 162 = 216.