iterate values of x through the difference between 2 functions equal to 40. the final x must make the equations equal to 40

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Sebastian Arias 2016-7-18

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评论： Sebastian Arias 2016-7-19

hi guys this is what i have so far. I am not sure how to make it test values of x until the function equals 40. Abs(F1-F2)=40

x=linspace(0,10,100);
F1=3*x+6;
F2=x.^2-log(x);
figure(2)
plot(x,F1,x,F2)
m=40;
w=abs(F1-F2);
if m=w

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Azzi Abdelmalek 2016-7-18

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[~,idx]=min(abs(w-m))
out=w(idx)

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Azzi Abdelmalek 2016-7-18

在 MATLAB Online 中打开

What If is doing in your code?

x=linspace(0,10,100);
F1=3*x+6;
F2=x.^2-log(x);
figure(2)
plot(x,F1,x,F2)
m=40;
w=abs(F1-F2);
[y,idx] = min(abs(w-m));
out = w(idx); 
x(idx)

Sebastian Arias 2016-7-19

ok i was trying to use if statements to try and get the same answer. thank you so much guys i really appreciate it!

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Walter Roberson 2016-7-18

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There are two roots for that, one roughly 1E-20 and the other roughly 8.6. Both of them are irrational and so will never be found by using linspace() on any finite number of points and testing for equality with 40. You will need to use a different approach such as fzero or solving symbolically.