Gp - 80

Sum of the first four members of a geometric progression is 80. Determine they if we know that the fourth member is nine times greater than the second.

Result

a1 =  2
a2 =  6
a3 =  18
a4 =  54
b1 =  -4
b2 =  12
b3 =  -36
b4 =  108

Solution:

Solution in text a1 =
Solution in text a2 =
Solution in text a3 =
Solution in text a4 =
Solution in text b1 =
Solution in text b2 =
Solution in text b3 =
Solution in text b4 =

Try another example






Leave us a comment of example and its solution (i.e. if it is still somewhat unclear...):

Showing 0 comments:
1st comment
Be the first to comment!
avatar




To solve this example are needed these knowledge from mathematics:

Next similar examples:

  1. Eight palm
    palma There grows 8 palms by the sea. At the first sitting one parrot, on second two, on third sits four parrots on each other twice the previous parrots sitting on a previous palm. How many parrots sitting on eighth palm?
  2. GP - 8 items
    fn Determine the first eight members of a geometric progression if a9=512, q=2
  3. Five members
    pst3.JPG Write first 5 members geometric sequence and determine whether it is increasing or decreasing: a1 = 3 q = -2
  4. Geometric sequence 4
    Koch_Snowflake_Triangles It is given geometric sequence a3 = 7 and a12 = 3. Calculate s23 (= sum of the first 23 members of the sequence).
  5. Six terms
    sequence_geo_3 Find the first six terms of the sequence a1 = -3, an = 2 * an-1
  6. Computer
    pc The computer was purchased 10000,-. Each year, the price of a computer depreciates always the same percentage of the previous year. After four years, the value of the computer is reduced to 1300,- How many percent was depreciated price of the computer each
  7. Quotient
    fun1_1 Determine the quotient and the second member of the geometric progression where a3=10, a1+a2=-1,6 a1-a2=2,4.
  8. Tenth member
    10 Calculate the tenth member of geometric sequence when given: a1=1/2 and q=2
  9. Piano
    piano If Suzan practicing 10 minutes at Monday; every other day she wants to practice 2 times as much as the previous day, how many hours and minutes will have to practice on Friday?
  10. Geometric progression 2
    exp_x There is geometric sequence with a1=5.7 and quotient q=-2.5. Calculate a17.
  11. Geometric progression
    fractal Fill 4 numbers between 4 and -12500 to form geometric progression.
  12. Geometric progression 4
    square_rot_1 8,4√2,4,2√2
  13. Ray
    luc-slnka Light ray loses 1/19 of brightness passing through glass plate. What is the brightness of the ray after passing through 7 identical plates?
  14. Theorem prove
    thales_1 We want to prove the sentense: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
  15. Power
    power Number ?. Find the value of x.
  16. Calculation
    pocty How much is sum of square root of six and the square root of 225?
  17. Powers
    1power Express the expression ? as the n-th power of the base 10.