At the same radius the escape speed-square is twice the circular speed-square, because escape needs exactly the kinetic energy that zeroes out the potential well. The factor of two is exact only for the stated gravity parameter and radius in the ideal circular two-body model. Real orbits add eccentricity, atmosphere/drag, perturbations, central-mass uncertainty, finite-body effects, and measurement uncertainty.
Escape speed-square is checked against the circular source. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The circular source speed-square is four
The circular speed-square source is 4.
vc2=4
Escape speed-square is twice circular speed-square