If P is a point on the ellipse whose foci are S and S′, then PS + PS′ = 8.
False
We have definition of the ellipse is
From the definition of the ellipse, we know that sum of the distances of any point P
on the ellipse from the two foci is equal to the length of the major axis.
Here major axis=2b=2*5=10
S and S'are foci, then SP+S'P=10