If the sum of three numbers in A.P., is 24 and their product is 440, find the numbers
If the sum of three numbers in A.P., is 24 and their product is 440, find the numbers

We should think about the three numbers in A.P. as

    \[\mathbf{a}\text{ }\text{ }\mathbf{d},\text{ }\mathbf{a},\text{ }\mathbf{and}\text{ }\mathbf{a}\text{ }+\text{ }\mathbf{d}.\]

Then, at that point, from the inquiry we have

    \[\left( \mathbf{a}\text{ }\text{ }\mathbf{d} \right)\text{ }+\text{ }\left( \mathbf{a} \right)\text{ }+\text{ }\left( \mathbf{a}\text{ }+\text{ }\mathbf{d} \right)\text{ }=\text{ }\mathbf{24}\text{ }\ldots \text{ }\left( \mathbf{I} \right)\]

    \[\mathbf{3a}\text{ }=\text{ }\mathbf{24}\]

    \[\therefore \mathbf{a}\text{ }=\text{ }\mathbf{8}\]

Also,

    \[\left( \mathbf{a}\text{ }\text{ }\mathbf{d} \right)\text{ }\left( \mathbf{a}\text{ }+\text{ }\mathbf{d} \right)\text{ }=\text{ }\mathbf{440}\text{ }\ldots \text{ }\left( \mathbf{ii} \right)\]

    \[\left( \mathbf{8}\text{ }\text{ }\mathbf{d} \right)\text{ }\left( \mathbf{8} \right)\text{ }\left( \mathbf{8}\text{ }+\text{ }\mathbf{d} \right)\text{ }=\text{ }\mathbf{440}\]

    \[\left( \mathbf{8}\text{ }\text{ }\mathbf{d} \right)\text{ }\left( \mathbf{8}\text{ }+\text{ }\mathbf{d} \right)\text{ }=\text{ }\mathbf{55}\]

    \[\mathbf{64}\text{ }\text{ }\mathbf{d2}\text{ }=\text{ }\mathbf{55}\]

    \[\mathbf{d2}\text{ }=\text{ }\mathbf{64}\text{ }\text{ }\mathbf{55}\text{ }=\text{ }\mathbf{9}\]

    \[\therefore \mathbf{d}\text{ }=\text{ }\pm \text{ }\mathbf{3}\]

In this way,

At the point when

    \[\mathbf{d}\text{ }=\text{ }\mathbf{3}\]

, the numbers are

    \[\mathbf{5},\text{ }\mathbf{8},\text{ }\mathbf{and}\text{ }\mathbf{11}\]

 and

At the point when

    \[\mathbf{d}\text{ }=\text{ }\text{ }\mathbf{3}\]

, the numbers are

    \[\mathbf{11},\text{ }\mathbf{8},\text{ }\mathbf{and}\text{ }\mathbf{5}\]

.

In this way, the three numbers are

    \[\mathbf{5},\text{ }\mathbf{8},\text{ }\mathbf{and}\text{ }\mathbf{11}\]

.