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Finding a root of an quadratic equation?
2x² + kx - 12 = 0; Root 1 = 3/2
How do I find root 2?
Thanks.
4 Answers
- Moise GunenLv 71 decade agoFavorite Answer
product of roots =-12/2 = -6
the second root = -6/(3/2)= -4
Another way
if 3/2 its a root then
2(3/2)^2+3k/2-12=0
9/2+3k/2-12=0
9+3k-24=0
3k = 15
k = 5
equation
2x^2+5x-12= (2x-3)(x+4) the second root x = -4
- 1 decade ago
You know that one root = 3/2. The '/2' part comes from the part of the quadratic with the constant term 2. Therefore that part was (2x-3) = 0 which solves to make x = 3/2.
So if the term independent of x is (-12) from the original equation, something multiplied by (-3) = 12.
Therefore the second root = 12/(-3) = - 4.
Source(s): None. - workoutgirl1235Lv 61 decade ago
ax² + bx + c = 0
The sum of the roots is -b/a, and the product of the roots is c/a.
The product of the roots of this equation is -12/2 = -6.
(3/2)r = -6
r = -6 * (2/3) = -4
