- #1
Fractal314
- 14
- 0
Homework Statement
I am unsure what to do here. I'm given the equation 5(x+1)3 = -5 , and I was given the equation 5(x+1)3 = 0 beforehand. The latter equation has an 'x' value of -1 only, right. However, for the former equation, because I brought the '-5' across the equal sign I realize the roots are not just -1 anymore.
The Attempt at a Solution
5(x+1)3 = -5
5(x+1)(x+1)(x+1)+5 = 0
5x3+15x2+15x+5+5 = 0
5(x3 + 3x2 + 3x + 2) = 0
But after this I'm lost.
If I factor:
5x2(x-5)+5(3x+2) = 0 then I have (x-5) which means x = 5, but I'm lost as to where I go next since there should be three roots. (3x+2) gives me x = -2/3.
But when I do the 5x2 +5 [should I get this?] I end up with x = sqrt(-1). I don't understand what this is supposed to mean. I figure I must have gone wrong somewhere.