Quadratic equation optained from modelling a pH process

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this is a quadratic equation optained from modelling a pH process.
[tex]2v10^{-3pH(t)}+10^{-2pH(t)}[2vk_a+2F_2C_2t-F_1^{2}(t)-x_b^{2}(t)(F_2+1)][/tex][tex]+10^{pH(t)}[2k_aF_2C_2t-2v-k_ac_1F_1^{2}(t)[/tex][tex]+x_a^{2}(t)-x_b^{2}(t))k_a(F_2+1)]-2vk_ak_w=0[/tex]

from this equation i need pH(s)/F_1(s).

the given equation is in time domain,i need my answer in laplace form.
here [tex]v,F_2,C_1,C_2,k_a,k_w[/tex] are all constant
[tex]v=1000,f_2=512,C_1=.32,C_2=.05.[/tex]

please help?