## Trending News

Promoted

# solve each polynomial?

4x^2-121=0

3x^4+12x^3-3x^2=12x

x^4+x^3-x^2-x=0

8x^3-27=0

Find the answers and I would like you to show your work. Will pick best answer ASAP.

### 1 Answer

Relevance

- 8 years agoFavorite Answer
1)

4x^2 -121 = 0

4x^2 = 121

x^2 = 30.25

x = 5.5, -5.5

2)

3x^4 + 12x^3 - 3x^2 = 12x

Right away we realize there is an 'x' term on every side so we can divide by an x and drop one

3x^3 + 12x^2 - 3x = 12

3x^3 + 12x^2 - 3x - 12 = 0

3x^2(x + 4) -3(x+4) = 0

(3x^2-3) (x+4) = 0

3x^2 - 3 = 0

3x^2 = 3

x^2 = 1

x = +/- 1

x+4 = 0

x = -4

so our roots are (-1,1,-4)

3)

x^4+x^3-x^2-x = 0

x(x^3+x^2-x-1) = 0

x^3+x^2-x-1 = 0

x^2 (x+1) -1(x+1) = 0

(x^2-1) (x+1) = 0

x = -1,1

4)

8x^3 - 27 = 0

8x^3 = 27

x^3 = 27/8

x = (27/8) ^ (1/3) (cube rooted)

x = 1.5

Still have questions? Get your answers by asking now.