How can I pick only first solution of equation

I made measurements and used them to plot x against y and found function that would describe the plot.

p1 = 258787.8788

p2 = -650125.2525

p3 = 577986.6667

p4 = -227435.083

p5 = 35645.6381

syms x

y = p1*x^4 + p2*x^3 + p3*x^2 + p4*x + p5 == pow

S = vpasolve (y,x)

I use variable 'pow' but lets say right now pow = 1430.

As a soultion I get 4 different values (as expected) but I only need the first one further on in the project. Its always the first one and values are too close to each other to put any assumptions which I tried.

Is there any way to make matlab ignore the three other solutions or anything that would give me similar results?

Thanks in advance for all the help :)

Answer 1

[Walter Roberson]

S(1)

You should also be considering

 roots([p1, p2, p3, p4, p5])