Question:
The sum of the squares of three consecutive natural number is 149. Find the numbers.
Solution:
Let three consecutive integer be $x,(x+1)$ and $(x+2)$
Then according to question
$x^{2}+(x+1)^{2}+(x+2)^{2}=149$
$x^{2}+x^{2}+2 x+1+x^{2}+4 x+4=149$
$3 x^{2}+6 x+5-149=0$
$3 x^{2}+6 x-144=0$
$3 x^{2}+6 x-144=0$
$3\left(x^{2}+2 x-48\right)=0$
$x^{2}+2 x-48=0$
$x^{2}+8 x-6 x-48=0$
$x(x+8)-6(x+8)=0$
$(x+8)(x-6)=0$
$(x+8)=0$
$x=-8$
Or
$(x-6)=0$
$x=6$
Since, x being a positive number, so x cannot be negative.
Therefore,
When $x=6$ then other positive integer
$x+1=6+1$
$=7$
And
$x+2=6+2$
$=8$
Thus, three consecutive positive integer be $6,7,8$