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山無語銀蟲 (著名寫手)
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[求助]
求大神們幫我解一下方程吧,高中數(shù)學(xué)都還給老師了 已有2人參與
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3.53=A/(1+B*EXP(-K*52) 6.17=A/(1+B*EXP(-K*67) 16.34=A/(1+B*EXP(-K*82) 就是三個未知數(shù)三個方程,可是我忘了怎么求exp了,求大神給個公式吧,就是A=公式,B=公式,K=公式,方便我算其他組的數(shù)據(jù),萬分感謝啊。 |
銀蟲 (著名寫手)
銀蟲 (著名寫手)
專家顧問 (職業(yè)作家)
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專家經(jīng)驗(yàn): +831 |
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建議用Matlab解! >> syms K B A >> f1=3.53-A/(1+B*exp(-K*52)) f1 = 353/100-A/(1+B*exp(-52*K)) >> f2=6.17-A/(1+B*exp(-K*67)) f2 = 617/100-A/(1+B*exp(-67*K)) >> f3=16.34-A/(1+B*exp(-K*82)) f3 = 817/50-A/(1+B*exp(-82*K)) >> [A B K]=solve(f1,f2,f3,'A','B','K') A = [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] [ -595405/261484] B = [ -37620240668060376629248/1577379504542829242672938041*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(cos(2/15*pi)+i*cos(11/30*pi))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(cos(4/15*pi)+i*cos(7/30*pi))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(1/4*5^(1/2)-1/4+1/4*i*2^(1/2)*(5+5^(1/2))^(1/2))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-cos(7/15*pi)+i*cos(1/30*pi))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-1/2+1/2*i*3^(1/2))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-1/4*5^(1/2)-1/4+1/4*i*2^(1/2)*(5-5^(1/2))^(1/2))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-cos(1/15*pi)+i*cos(13/30*pi))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-cos(1/15*pi)-i*cos(13/30*pi))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-1/4*5^(1/2)-1/4-1/4*i*2^(1/2)*(5-5^(1/2))^(1/2))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-1/2-1/2*i*3^(1/2))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(-cos(7/15*pi)-i*cos(1/30*pi))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(1/4*5^(1/2)-1/4-1/4*i*2^(1/2)*(5+5^(1/2))^(1/2))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(cos(4/15*pi)-i*cos(7/30*pi))^7*119667^(8/15)*143792^(7/15)] [ -37620240668060376629248/1577379504542829242672938041/(cos(2/15*pi)-i*cos(11/30*pi))^7*119667^(8/15)*143792^(7/15)] K = [ -log(1/143792*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(cos(2/15*pi)+i*cos(11/30*pi))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(cos(4/15*pi)+i*cos(7/30*pi))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(1/4*5^(1/2)-1/4+1/4*i*2^(1/2)*(5+5^(1/2))^(1/2))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-cos(7/15*pi)+i*cos(1/30*pi))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-1/2+1/2*i*3^(1/2))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-1/4*5^(1/2)-1/4+1/4*i*2^(1/2)*(5-5^(1/2))^(1/2))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-cos(1/15*pi)+i*cos(13/30*pi))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-cos(1/15*pi)-i*cos(13/30*pi))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-1/4*5^(1/2)-1/4-1/4*i*2^(1/2)*(5-5^(1/2))^(1/2))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-1/2-1/2*i*3^(1/2))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(-cos(7/15*pi)-i*cos(1/30*pi))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(1/4*5^(1/2)-1/4-1/4*i*2^(1/2)*(5+5^(1/2))^(1/2))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(cos(4/15*pi)-i*cos(7/30*pi))*119667^(1/15)*143792^(14/15))] [ -log(1/143792*(cos(2/15*pi)-i*cos(11/30*pi))*119667^(1/15)*143792^(14/15))] >> double(A) ans = -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 -2.2770 >> double(B) ans = -3.1094 3.0415 + 0.6465i -2.8406 - 1.2647i 2.5156 + 1.8277i -2.0806 - 2.3108i 1.5547 + 2.6928i -0.9609 - 2.9572i 0.3250 + 3.0924i 0.3250 - 3.0924i -0.9609 + 2.9572i 1.5547 - 2.6928i -2.0806 + 2.3108i 2.5156 - 1.8277i -2.8406 + 1.2647i 3.0415 - 0.6465i >> double(C) ??? Undefined function or variable 'C'. >> double(K) ans = 0.0122 0.0122 - 0.4189i 0.0122 - 0.8378i 0.0122 - 1.2566i 0.0122 - 1.6755i 0.0122 - 2.0944i 0.0122 - 2.5133i 0.0122 - 2.9322i 0.0122 + 2.9322i 0.0122 + 2.5133i 0.0122 + 2.0944i 0.0122 + 1.6755i 0.0122 + 1.2566i 0.0122 + 0.8378i 0.0122 + 0.4189i >> A(1) ans = -595405/261484 >> double([A(1);B(1);K(1)]) ans = -2.2770 -3.1094 0.0122 最后的是實(shí)數(shù)解! |

木蟲之王 (文學(xué)泰斗)
peterflyer
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3.53=A/(1+B*EXP(-K*52) (1) 6.17=A/(1+B*EXP(-K*67) (2) 16.34=A/(1+B*EXP(-K*82) (3) (2)/(1): 6.17/3.53=(1+B*EXP(-K*52)/(1+B*EXP(-K*67) B=2.64/{3.53*exp(-K*52)-6.17*exp(-K*67)} (4) (3)/(1): 16.34/3.53=(1+B*EXP(-K*52)/(1+B*EXP(-K*82) (5) 將(4)帶入(5): 16.34/3.53={1+2.64*exp(-K*52)/{3.53*exp(-K*52)-6.17*exp(-K*67)}/{1+2.64*EXP(-K*82)/{3.53*exp(-K*52)-6.17*exp(-K*67)}} 整理后得: 16.34/3.53=6.17*[1-exp(-15*k)]/[3.53-6.17*exp(-15*k)+2.64*exp(-30*k)] 令u=exp(-15*k) (6) 16.34/(3.53*6.17)=[1-u]/[3.53-6.17*u+2.64*u^2] 0.7502261238*[3.53-6.17*u+2.64*u^2]=[1-u] 1.98059697*u^2-3.62889518*u+1.64829822=0 u={3.62889518±sqrt[-3.62889518]}/[2*1.98059697] 由此得到兩個u值。代入(6)可得兩個k值。再代入(4)得到兩個B值。然后代入(1)(2)(3)中的任何一個式子得到兩個A值。 |
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木蟲 (正式寫手)
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