roots of quadratic equations (1 Viewer)

[Cattle]

hey everyone i have a question does anyone know how to do this or what the answer is....

The roots of a quadratic equation pX2 - x + q = 0 are -1 and 3. find p and q

 

[SoulSearcher]

Using sums and product of roots
-1 + 3 = 1/p
(-1)*3 = p/q

Then solve from there.

 

[pLuvia]

Or you could sub in the roots you are given and the equation should equal zero and then solve simultaneously

i.e.
p+1+q=0 (1)
9p-3+q=0 (2)

 

[Forbidden.]

hey everyone i have a question does anyone know how to do this or what the answer is....

The roots of a quadratic equation pX2 - x + q = 0 are -1 and 3. find p and q

MERRY CHRISTMAS

Teh n00b way:

px² - x + q = 0

a = p
b = -1
c = q

(alpha) is - 1
(beta) is 3

Sum of roots: (alpha) + (beta) = -b/a

(-1) + (3) = - b/a
2 = - (-1)/p
2 = 1/p

p = 0.5

Product of roots: (alpha) x (beta) = c/a

(-1) x (3) = q/p

-3 = q/p

q = -3p

But p =1/2

q = -3(1/2)

q = -1.5