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[fullonoob]

Solve the equation x^4 + 4x^3 + 5x^2 + 2x - 20 = 0

If the equation x^3 + 3px + q = 0 has double root for p< 0 and q>0, prove that q^2 + 4p^3 = 0

many thanks

 

[fullonoob]

So or

For the other one, the double root will be a root of the derivative, so and .

So



So

thx but for the first one how'd you know it = (x^2+2x-4)(x^2+2x+5)=0 on the first step??

 

[fullonoob]

It's a bit boring though.

See if you can solve exactly.

(The 1969 3 unit paper asked for the approximate solution to this using Newton's method, but you can actually solve it exactly.)

answer that one please xDD

 

[xV1P3R]

It's a bit boring though.

See if you can solve exactly.

(The 1969 3 unit paper asked for the approximate solution to this using Newton's method, but you can actually solve it exactly.)

I too would like to know!

 

[adomad]

Somewhat uglier, but equivalent expressions from wolframalpha.com yield the four roots, the last two of which are the complex roots:

have you tried getting a Girl friend to fill in your spare time?

 

[fullonoob]

wtf is this O_O
has it been removed from the new syllabus?
never encountered any such question
i dont even really wna read the working out cos its so long xD