0

# how do you write a quadratic function with zeros 3/7 and -4?

3/7 and -4

### 2 Answers by Expert Tutors

Parviz F. | Mathematics professor at Community CollegesMathematics professor at Community Colle...
4.8 4.8 (4 lesson ratings) (4)
0
Postulate :Every quadratic of aX2 + bX + c   has roots of m, n if and only if
aX2 +bX +c  can be  factored into  ( x -m ) ( X -n)
accordingly :
f(x) = ( X +4) ( X -3/7) = X2 + 4X -3/7X - 12/7
7X2 +28X - 3X - 12=
7X2 + 25X - 12
Justin L. | A Personalized Approach to a Standardized EducationA Personalized Approach to a Standardize...
5.0 5.0 (7 lesson ratings) (7)
0
if they give you the zeroes (also called roots) you can get the function ax^2+bx+c
by using the product of the roots and the sum of the roots

the sum of the roots will come out to be -b/a

the product of the roots is c/a

so the sum of your roots in your case (3/7 - 4) would be -25/7

the product of your roots 3/7 * -4 would be -12/7

so we have sum of roots -25/7 = -b/a
product of roots -12/7 = c/a

you can match up the a, b and c
a=7  b=25 (watch your signs) and c=-12
7x^2+25x-12