Polynomials question (1 Viewer)

[Examine]

Find the points of intersection between the polynomial P(x)=x^3+5x^2+4x-1 and the line 3x+y+4=0.

How would you answer this question? I was thinking of how you would approach the ones where they both equal 0 and substitute them in though that obviously wouldn't work. Is there something I'm missing?

 

[deswa1]

Equate the two to find P.O.I ->x^3+5x^2+4x-1=-3x-3
x^3+5x^2+7x+2=0

By inspection, x=-2 is a root -> x+2 is a factor
Factorise:
(x+2)(x^2+3x+1)=0
Then solve the quadratic for other two

Find y coordinates once you have the x ones

 

[RealiseNothing]

Equate the two to find P.O.I ->x^3+5x^2+4x-1=-3x-3
x^3+5x^2+7x+2=0

By inspection, x=-2 is a root -> x+2 is a factor
Factorise:
(x+2)(x^2+3x+1)=0
Then solve the quadratic for other two

Find y coordinates once you have the x ones

-3x-4*

 

[Examine]

Equate the two to find P.O.I ->x^3+5x^2+4x-1=-3x-3
x^3+5x^2+7x+2=0

By inspection, x=-2 is a root -> x+2 is a factor
Factorise:
(x+2)(x^2+3x+1)=0
Then solve the quadratic for other two

Find y coordinates once you have the x ones

Oh right lol ~oops~

Gratz on getting AAA deswa (pretty much guaranteed for comm/law now ) and gl with the hsc.

 

[deswa1]

-3x-4*

Haha whoops- that means my answer is wrong

The method is the thing though lol (I'm a retard)- surprised it still worked though