Symbolic variables and equations. Beginner

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Jessica
Jessica 2011-11-1
I've just started using matlab and am having a problem understanding what this question wants and the commands i need to use to solve it.
Create the symbolic variables
a b c d x
and use them to create the following symbolic expressions:
se1 = x^3 -3*x^2 +x
se2 = sin(x) + tan(x)
se3 =(2*x^2 - 3*x - 2)/(x^2 - 5*x)
se4 = (x^2 -9)/(x+3)
The question wants me to write the commands I used in MATLAB with comments.
So far all I can think to do is
syms a b c d x
and maybe something with the solve function. although i have no idea what to do or where to start.
Thanks for any help.

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回答（1 个）

William
William 2011-11-1
clc
clear
syms a b c d x
se1 = x^3 -3*x^2 +x
se2 = sin(x) + tan(x)
se3 =(2*x^2 - 3*x - 2)/(x^2 - 5*x)
Type
help syms
se4 = (x^2 -9)/(x+3)
if you want to plot them type:
help ezplot
  2 个评论
Jessica
Jessica 2011-11-1
i understand defining the variable with syms a b c d x
i also understand typing se1, se2, se3, and se4 into matlab
Its from there that i don't know what to do. it wants me to create the symbolic expressions using the symbolic variables. I have no idea how to do that.
Its not asking for a graph. Just the matlab commands.
Walter Roberson
Walter Roberson 2011-11-1
se1 = x^3 -3*x^2 +x
and so on _is_ the method you use to create a symbolic expression using the symbolic variables.
The assignment doesn't seem to have much point to it ;-)

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