Posted by **Alissa** on Tuesday, December 20, 2011 at 8:02pm.

solve the inequality express in interval notation

x^4 + 4x^3 - 9x^2 - 36x < 0

- Algebra -
**Writeacher**, Tuesday, December 20, 2011 at 8:04pm
Assistance needed.

- Alegra -
**Alissa**, Tuesday, December 20, 2011 at 9:32pm
Ah yeah which is why I post the question.

- Alegra -
**Ms. Sue**, Tuesday, December 20, 2011 at 9:47pm
Alissa -- Writeacher corrected your spelling of "Algebra" so that a math expert would see your post.

Jiskha doesn't have any experts in Alegra (whatever that is).

- Alegra -
**Steve**, Wednesday, December 21, 2011 at 11:05am
x^4 + 4x^3 - 9x^2 - 36x

= x(x^3 + 4x^2 - 9x - 36)

Cubics are hard to solve, so look for easy roots. They will be factors of 36.

A little synthetic division reveals

(x+4)(x+3)x(x-3)

Now since everything is single roots, the graph alternates between positive and negative between roots.

Since it's a quartic with a positive coefficient, it will be positive before the lowest root and after the highest root.

So,

y > 0 for x < -4

y < 0 for -4 < x < -3

y > 0 for -3 < x < 0

y < 0 for 0 < x < 3

y > 0 for x > 3

- Alegra -
**Alissa**, Wednesday, December 21, 2011 at 3:02pm
Thank you I appreciate your help and the fact that you didn't make a big issue out of a typo. Again thank you.

## Answer this Question

## Related Questions

- algebra - solve the inequality express in interval notation x^4 + 4x^3 - 9x^2 - ...
- Solve Inequality - Solve the inequality. Express your solution using interval ...
- Math Homework - Solve the inequality and express the answer in interval notation...
- pre cal - solve the inequality express your solution in interval notation (x - 4...
- Math - Solve the inequality by first rewriting it as an equivalent inequality ...
- precalculus - solve the inequality express your solution using interval notation...
- calculus - use a sign chart to solve inequality. Express answers in interval ...
- algeb collage - solve the inequality,express using interval notation x3-5x2-14x&...
- pre-calculus - please help me with thisone thanks solve the inequality ...
- Math - Problem4 - Solve the inequality. Express your solution using interval ...