# How to find an equilibrium point between two lines?

5 views (last 30 days)
Joao Pereira on 26 Dec 2019
Commented: Rena Berman on 14 May 2020
Hi guys could you help me find the equilibrium point between my demand and supply curves cheers.
This is the code I wrote, I tried using the command "solve", but I did not succeed
x = 1:20:14;
xticks(1:1:30)
y1 = -3*x +90;
plot (x,y1,'b')
hold on
x = 1:0.5:30;
y2 = 10+x;
plot (x,y2,'c')
hold on
x = 1:0.5:30;
y3 = -3*x +60;
plot (x,y3,'b')
plot (x,y1,y2,y3)
ylim([0 100])
hold on
legend ('0G demand curve','OG supply curve','tax(30)')
title ('Market Equilibrium')
xlabel('Quantitites')
ylabel('Price')
hold off
P = InterX([x1;y1],[x;y2]);
plot(x,y1,x,y2,P(1,:),P(2,:));
Rena Berman on 14 May 2020

Mark Sherstan on 26 Dec 2019
You were close! The x domain must be the same length and some of your variables were mislabeled. I quickly cleaned up your code and this should work for you:
x = 1:0.5:30;
y1 = -3*x +90;
y2 = 10+x;
y3 = -3*x +60;
plot(x,y1,'b', x,y2,'c', x,y3,'b')
ylim([0 100])
title ('Market Equilibrium')
xlabel('Quantitites')
ylabel('Price')
P12 = InterX([x;y1],[x;y2])'
P23 = InterX([x;y2],[x;y3])'
hold on
plot(P12(1,1),P12(1,2),'ro')
plot(P23(1,1),P23(1,2),'ko')
legend ('0G demand curve','OG supply curve','tax(30)','Intersection Y1-Y2', 'Intersection Y2-Y3')
hold off
Joao Pereira on 26 Dec 2019
Thank you Mark I was working with that function I’ll just keep trying
Mark Sherstan on 26 Dec 2019
As long as the function and my code is in the same folder it will work, I just tested it. So if you need more help just ask!

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