The sum of three numbers in A.P. is 24 and sum of their squares is 194 . Find the numbers?
Answers
Answer:
7 , 8 & 9
Step-by-step explanation:
Given :
The sum of three numbers in A.P is 24,.
The sum of their squares is 194.
To find :
The 3 numbers.
Solution :
As they are in A.P , they must be of the form : (a - d) , a & (a + d)
Hence, their sum :
⇒ (a - d) + a + (a - d) = 24
⇒ 3a = 24 ⇒ a = 8,.
Hence, the middle (or 2nd) term is 8,.
_
The sum of their squares will be,
⇒ (a - d)² + a² + (a + d)² = 194
⇒ (8 - d)² + 8² + (8 + d)² = 194
⇒ (8 - d)² + (8 + d)² = 194 - 64
⇒ 2(8² + d²) = 130
⇒ 128 + 2d² = 130
⇒ 2d² = 13 0 - 128 = 2
⇒ 2d² = 2
⇒ d² = 1 ⇒ d = ±1
Hence, the numbers must be ,
(8 ∓ 1) , 8 , (8 ± 1)
⇒ The numbers are 7 , 8 & 9 respectively,.
Let the three numbers be a-d, a and a+d.
According to the question,
➡a-d+a+a+d=24
➡3a=24
➡a=8
Now,
Sum of their squares=194
➡(a-d)²+(a)²+(a+d)²=194
➡(8-d)²+(8)²+(8+d)²=194
➡64+d²-16d+64+64+d²+16d=194
➡192+2d²=194
➡2d²=2
➡d²=1
➡d=±1
Thus, the the numbers are
➡a-d=8-1=7
➡a=8
➡a+d=9
↪7,8,9....