Q. 64.0( 19 Votes )

# Find three numbers in AP whose sum is 15 and product is 80.

Answer :

Let the numbers be (a - d), a, (a + d).

Now, sum of the numbers = 15

(a - d) + a + (a + d) = 15

3a = 15

a = 5

Now, product of the numbers = 80

(a - d) × a × (a + d) = 80

a3 - ad2 = 80

Put the value of a, we get,

125 - 5 d2 = 80

5 d2 = 125 - 80 = 45

d2 = 9

d = � 3

If d = 3, then the numbers are 2, 5, 8.

If d = - 3, then the numbers are 8, 5, 2.

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