# Exercici 07.13

## apartat a)

kill(all)$

Eq1: y = 4*x^3 + 3*x^2 + 2*x +1;

depends(y,x);

diff(Eq1,x);

Dy(x):=12*x^2+6*x+2;

Eq2: 2*x - y + 8 = 0;       solve(Eq2, y);

m=m:2;      Eq3: m=12*x^2+6*x+2;    solve(Eq3, x);

x1=x1:-1/2$     [x1, Dy(x1)];
x2=x2:0$         [x2, Dy(x2)];

## apartat b)

Eq3: 4*x +5*y + 75 = 0;       solve(Eq3, y);

m2=m2:-4/5;      Eq4: -1/m2=12*x^2+6*x+2;    solve(Eq4, x);

x3=x3:-1/4$     [x3, Dy(x3)];