> y:=x^2;

> z:=x^4;

>

> w:=x^6;

> plot({y,z,w},x=-1..1);

>

> y+x=9;

y+x = 9

> 6*y+3*x=45;

6*y+3*x = 45

> solve({x+y=9,6*y+3*x=45},{x,y});

{y = 6, x = 3}

> solve(y+x=9,y);

-x+9

> solve(6*y+3*x=45,y);

-1/2*x+15/2

> plot({-x+9,-1/2*x +15/2},x=-5..5);

For a simulatenous equation system, there must be as many equations as there are variables for the system to

be exactly identified. If ethere are more equations than there are variables, the system is overidentified. Similarly, if there are more variables than there are equations, the system is underidentified.

IS-LM Model: page 22.

Given:

C:=48 +0.8*y,

I:=98-75*i,

Ms:=250, and Mt:=0.3*y and Mz=52-150*i, Find the equilibrium level of income--y, interest

rate--i and money demands: Mt and Mz.

Here is a plot of the 45 degree line and the consumption function.

> plot({x,48+.8*x},x=0...1000.0);

To find equilibrium we have to solve the following simulatenous equations:

> solve({0.2*y+75*x= 146, 0.3*y -150*x=198},{x,y});

>

> plot(98-75*i,i=0.1..0.8);

>

> Y:=C+I;

Clear;

> Ms:=Md;

> 250=0.3*yd+52-150*i;

> yd=48+0.8*yd+98-75*i;

> solve({250=0.3*yd+52-150*i,yd=48+0.8*yd+98-75*i},{yd,i});

> consumptoon:=48+0.8*700;

> Investment:=98-75*(0.08);

> Savings=Investment;

> 92+608;

>

>

> y:=x^2+6*x+13;

> factor(x^2+6*x+13);

> y:=(x^2+6*x+9)+4;

> solve((x^2+6*x+9)+4);

> plot(x^2+6*x+13,x=-5..10);

> plot(x^2+6*x-13,x=-5..10);

>