Find the sum of all real values of satisfying the above equation.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
Let y = x x 2 + 1 . Then the given equation becomes
y + y 1 = 1 0 2 9 ⟹ 1 0 y 2 − 2 9 y + 1 0 = 0 ⟹ ( 2 y − 5 ) ( 5 y − 2 ) = 0 ,
and so either y = 2 5 or y = 5 2 .
Now y = x x 2 + 1 = 2 5 ⟹ 2 x 2 − 5 x + 2 = 0 ⟹ ( 2 x − 1 ) ( x − 2 ) = 0 ,
and so either x = 2 or x = 2 1 , both of which satisfy the original equation.
Next, y = x x 2 + 1 = 5 2 ⟹ 5 x 2 − 2 x + 5 = 0 ,
which has no real solutions as the discriminant b 2 − 4 a c = ( − 2 ) 2 − 4 ∗ 5 ∗ 5 = − 9 6 < 0 .
Thus the sum of all real solutions x is 2 1 + 2 = 2 5 = 2 . 5 .