Idealistic
Junior Member
- Joined
- Sep 7, 2007
- Messages
- 97
I'm having a bit of trouble. I found the x intercepts for a quartic equation, then when I enter that equation in a graphing calculater the intercepts are different than what I found.
Here's what I'm given:
y = -(x - 3)(x + 1)(x - 2)^2
Therefore the intercepts are:
x = 3, x = -1, and x = 2 (a double root which touches the "x" axis rather than intersecting it).
Here's my math for finding the equation in general form:
y = -(x - 3)(x + 1)(x - 2)^2
y = -(x^2 - 2x -3)(x^2 - 4x - 4) **I just foiled the first two binomials, and the last two.
y = (-x^2 + 2x +3)(x^2 - 4x -4) **I just multiplied the negative one into the brackets.
y = -x^4 + 4x^3 + 4x^2 + 2x^3 - 8x^2 -8x + 3x^2 -12x - 12 **I just multiplies everything.
y = -x^4 + 6x^3 - x^2 - 20x - 12 **Combined like term.
when I enter that equation into my calculator, I get -1 as a double root, 3 as a single root, and 4.8ish as a single root.
where did I go wrong? In my math, or did I screw up initially with the roots at the top?
Here's what I'm given:
y = -(x - 3)(x + 1)(x - 2)^2
Therefore the intercepts are:
x = 3, x = -1, and x = 2 (a double root which touches the "x" axis rather than intersecting it).
Here's my math for finding the equation in general form:
y = -(x - 3)(x + 1)(x - 2)^2
y = -(x^2 - 2x -3)(x^2 - 4x - 4) **I just foiled the first two binomials, and the last two.
y = (-x^2 + 2x +3)(x^2 - 4x -4) **I just multiplied the negative one into the brackets.
y = -x^4 + 4x^3 + 4x^2 + 2x^3 - 8x^2 -8x + 3x^2 -12x - 12 **I just multiplies everything.
y = -x^4 + 6x^3 - x^2 - 20x - 12 **Combined like term.
when I enter that equation into my calculator, I get -1 as a double root, 3 as a single root, and 4.8ish as a single root.
where did I go wrong? In my math, or did I screw up initially with the roots at the top?