I need help getting the answers for these 2 questions!
I want to see if i did them right... (because i dont have an answer sheet)

1) Solve 12x^3 - 16x^2 + 7x -1
Let f(x) = 12x^3 - 16x^2 + 7x -1

2) Solve the inequality:
3x / (x^2 -4) < -1

*note: where the "<" is, its supposed to be less than/equal to. (i just cant find a key for it :P )

Thanks again!

2. Originally Posted by xo-hikari
I need help getting the answers for these 2 questions!
I want to see if i did them right... (because i dont have an answer sheet)

1) Solve 12x^3 - 16x^2 + 7x -1
Let f(x) = 12x^3 - 16x^2 + 7x -1

2) Solve the inequality:
3x / (x^2 -4) < -1

*note: where the "<" is, its supposed to be less than/equal to. (i just cant find a key for it :P )

Thanks again!
1) $\displaystyle 12x^3 - 16x^2 + 7x - 1 = 12x^3 - 12x^2 - 4x^2 + 3x + 4x - 1 = (12 x^3 - 12x^2 + 3x) - (4x^2 - 4x + 1)$ $\displaystyle = 3x(4x^2 - 4x + 1) - (4x^2 - 4x + 1) = \, ....$

2) Case 1: Solve $\displaystyle 3x \leq -(x^2 - 4)$ for $\displaystyle x^2 - 4 > 0 \Rightarrow x > 2 \, \text{or} \, x < -2$.

Case 2: Solve $\displaystyle 3x \geq -(x^2 - 4)$ for $\displaystyle x^2 - 4 \leq 0 \Rightarrow -2 \leq x \leq 2$.