49T+245e^(-T/5)-545 = 0

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jackery smith
jackery smith 2016-9-24
评论： Walter Roberson 2016-9-24
i am totally new to matlab. with which func and command could I get the value of T?
sorry for the too much elementary question. Just started to learn D.E.s..

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回答（3 个）

José-Luis
José-Luis 2016-9-24
编辑：José-Luis 2016-9-24
fzero()
fun = @(x) 49*x + 245*exp(-x/5) - 545;
result = fzero(fun,0)
Walter Roberson
Walter Roberson 2016-9-24
syms T
solution = solve(49*T+245*exp(-T/5)-545 == 0)
The answer will be in terms of the Lambert W function. If you want to see the decimal equivalent,
double(solution)
yubo liu
yubo liu 2016-9-24
I try the above methods,but why do i get different results,fun = @(x) 49*x + 245*exp(-x/5) - 545; result = fzero(fun,0) the first resule is -6.2180,and the second method syms T solution = solve(49*T+245*exp(-T/5)-545 == 0),the second result is 10.5116 why? hope your answers
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Star Strider
Star Strider 2016-9-24
When in doubt, plot it:
fun = @(x) 49*x + 245*exp(-x/5) - 545;
t = linspace(-15, 25, 500);
figure(1)
plot(t, fun(t))
grid
Walter Roberson
Walter Roberson 2016-9-24
There are, by the way, an infinite number of solutions; two of the solutions are real.

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