Find the roots of the polynomial equation.

-x3 + 5x2 - 11x + 55 = 0

Question

Find the roots of the polynomial equation.

-x3 + 5x2 - 11x + 55 = 0

anonymous · Answer

x^3 or x3?

anonymous · Answer

-x^3 + 5x^2 - 11x + 55 = 0

ddcamp · Answer

Here we should factor by grouping.
$$0=[-x^3+5x^2]+[-11x+55]$$
Pulling out the common factors on both sides, we're left with:
$$0=x^2(-x+5) + 11x(-x+5)$$
Which gives us:
$$0=(x^2+11x)((5-x)$$
Pulling an x out of the left term, we get
$$0= x(x+11)(5-x) $$

Now find the zeroes by setting each factor equal to zero

anonymous · Answer

I have no idea how to do that...

ddcamp · Answer

Honestly, factoring by grouping is something that they just put in the book for no good reason. It only works on specific equations, and you won't be using it much later on.

anonymous · Answer

Oh... that's... tragic >-< but that's a relief lol thank you