solve by substitution method
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4x+5y=-15
x=3-8y
回答（3 个）
Matt Fig
2011-3-16
0 个投票
Do you have a question? One related to MATLAB?
2 个评论
Matt Tearle
2011-3-16
attack of the Matt Police!
Matt Fig
2011-3-16
HaHa, I didn't even see your first comment till now!
Walter Roberson
2011-3-17
syms x y
yexpr = solve(4*x+5*y+15*x,y);
xval = solve(subs(3-8*y+15*x,yexpr),x);
yval = solve(subs(4*x + 5*y + 15*x, x, xval),y);
(There is at least one shorter method.)
omer ozdemir
2018-9-15
编辑：Walter Roberson
2018-9-15
how can be solved this problem?
suppose that a polynominal can be expressed by
f(x)= x^5+3*x^4+4*x^3+2*x^2+3*x+6
If one wants to substitute x by s-1/s+1, the function f(x) can be changed into a function of s.
thanks.
2 个评论
Walter Roberson
2018-9-15
You can use subs() and simplify() from the Symbolic toolbox.
Note that f(s) will not be a polynomial.
omer ozdemir
2018-9-16
thanks.
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2018-9-16
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