Say the equation is
ax3+bx2+cx+d=0
suppose that he roots of this equation are α,β, and γ.
How to prove that,
1) α+β+γ = -b/a
2) αβγ=d/a
Start by reading this: Vieta's Formulas -- from Wolfram MathWorld
Then use Google.
Hello, callkalpa!
Say the equation is: .
Suppose that the roots of this equation are: .
Prove that:
. .
. .
Divide the equation by .[1]
Since are roots, the equation has the form:
. .
which simplifies to:
. . .[2]
Equate coefficients of [1] and [2]:
. .
Therefore: .