Question

how to solve equation in comments?

Answer 1

\[7x^4-42x^2-35x=0\]

Answer 2

I get this far but I'm not sure what to do next:\[7x(x^3-6x-5)=0\]

Answer 3

1) factor out of 7, and didivide both sides by 7x, and will get one x-solution.
2) factor what you will have after step 1, and there are the answers.

Answer 4

I mean factor out of 7x

Answer 5

so go from x^3-6x-5=0 since 0/7x is 0?

Answer 6

factor it.

Answer 7

\(\large\color{teal}{ \rm x^3-6x-5=(x+1)(x^2-x-5) }\)

Answer 8

how did you factor that? I see how it works but I'm not sure how to do that on my own.

Answer 9

factorization is one of the things that I can't explain how I do it -:(

Answer 10

Well, for now you can go with this. So we divided both sides by 7x, and this one solution is z=0, can you find the remaining solutions ?

Answer 11

if i do synthetic division on it i get that. Yes, I see how to do it now. now that i have x=0 and -1 so far i use quadratic to get the last one.

Answer 12

yes, so you have left, \(\large\color{teal}{ \rm x^2-x-5=0 }\) and that you can't factor, I would suggest using the quadratic formula.

Answer 13

so the last answer (well answers really) is \[\frac{ -1 \pm 2\sqrt{5} }{ 2 }\]

Answer 14

or actually this:\[\frac{ -1 \pm \sqrt21 }{ 2 }\]

Answer 15

correct, except that 1 in-front of the √ is positive.

Answer 16

ah i forgot. thanks!

Answer 17

yw