Maths-
General
Easy

Question

If a comma blank b comma and c are in A.P. and b minus a comma blank c minus b and a are in G.P., then a colon b colon c is

  1. 1:2:3   
  2. 1:3:5   
  3. 2:3:4   
  4. 1:2:4  

The correct answer is: 1:2:3


    We have,
    2 b equals a plus c
    open parentheses c minus b close parentheses to the power of 2 end exponent equals left parenthesis b minus a right parenthesis a
    rightwards double arrow open parentheses b minus a close parentheses to the power of 2 end exponent equals open parentheses b minus a close parentheses a blank open square brackets 2 b equals a plus c blank rightwards double arrow b minus a equals c minus b close square brackets
    rightwards double arrow b equals 2 a
    rightwards double arrow c equals 3 a blank open square brackets U s i n g blank 2 b equals a plus c close square brackets
    rightwards double arrow a colon b colon c equals 1 colon 2 colon 3

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