SOLUTION: How to show that if X1 and X2 are the two roots of {{{ ax^2+bx+c=0 }}} , then {{{ X1X2=c/a }}} and X1+X2=-b/a , where a is not equal 0 ?

Question 1058234: How to show that if X1 and X2 are the two roots of , then
and X1+X2=-b/a , where a is not equal 0 ?
Found 2 solutions by josmiceli, Boreal:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
(1)
Divide both sides by

----------------------------
Roots are , and

(2)
Comparing (1) and (2),

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
x1=(1/2a)(-b+ sqrt(b^2-4ac))
x2=(1/2a)(-b-sqrt(b^2-4ac))
Their sum is (1/2a)(-2b)=-b/a
Their product is foiling a difference of squares.
That is (1/4a^2)*{b^2-(b^2-4ac)}=4ac/4a^2=c/a, a NE 0
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