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Help with quadratic function problem?
Having trouble with this problem
find a quadratic function who x intercepts are -3 and 1 and a is 2
7 Answers
- 1 decade agoFavorite Answer
2(x^2+2x-3)=y
x=-3
(x+3)=0
x=1
(x-1)=0
(x+3)(x-1)=0
(x^2+2x-3)=y Times by 2.
2(x^2+2x-3)=y
Answer is 2x^2+4x-6=y
- Anonymous1 decade ago
If -3 is an x-intercept, then the function has (x+3) as a factor (plugging x=-3 will give f(-3)=0).
Another factor is (x-1) for our other intercept x=1.
Multiplying these two factors gives a coefficient of 1 for x² so you need to double it to get a=2.
Answer: f(x) = 2(x+3)(x-1) = 2x² + 4x - 6.
- 1 decade ago
you would take x=-3 and x=1
so y=(x+3)(x-1)
then y=x^2 -x +3x -3
y=(x^2)+2x-3
but we need a to equal 2 so we times it all by 2 and get
y=2(x^2)+4x-6
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- shellbeeLv 51 decade ago
you have to use the quadratic equation:
x= the opposite of b plus or minus radical (square root) b squared minus 4 ac over 2a. (hey!)
a is the first number so you plug that in to the 4ac and 2a.
- OrinocoLv 71 decade ago
the a is a 2??? *boggles*
as in the y = Ax^2 + Bx + C .... the A = 2?
then (-B +/- SQRT(B^2 - 4AC))/2A = -3 and 1
B = 4
SQRT(16 - 8C) = 2
16 - 8C = 4
C = 3/2
y = 2x^2 + 4X + 3/2