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Proportional Fourth


Dice three rational numbers a, b and ç, non-null, is called fourth proportional of these numbers a number x such that:

Example:

  • Determine the fourth proportional of the numbers 8, 12, and 6.
    Solution: We indicate by x the fourth proportional and we set the proportion:
    (applying the fundamental property)
    8 x = 12. 6th
    8 x = 72
    x = 9
    So the fourth proportional is 9.
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