HP PRIME solves a equation wrongly

[Williams369]

We write in the CAS

"csolve(((x+400)*0.8/(π*0.04^4/32)) = (0.4*((x+400)*0.8/(π*0.04^4/32)+x*0.5/(0.141*(20*√2)^4*10^-12))),x)" RESULT −1661.90655858

"zeros(((x+400)*0.8/(π*0.04^4/32)) = (0.4*((x+400)*0.8/(π*0.04^4/32)+x*0.5/(0.141*(20*√2)^4*10^-12))),x)" RESULT −1661.90655858


"fsolve(((x+400)*0.8/(π*0.04^4/32)) = (0.4*((x+400)*0.8/(π*0.04^4/32)+x*0.5/(0.141*(20*√2)^4*10^-12))),x)" RESULT 2492.85983787

Plugging "−1661.90655858" into the equation, the result is nonzero. It is a linear equation, how can it solve it wrong.

The correct answer is the one provided by fsolve. Why is this so? Why is HP Prime wrong when solving a simple equation of the first degree?