## anonymous one year ago 8x2 + 64x = 0

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1. e.mccormick

I am guessling that is 8x^2... So, what problem are you having with it?

2. anonymous

the answers choices are x=0 ,x=-8 x=0,x=8 x=-8,x=0,x=8 x=8,x=64

3. anonymous

@e.mccormick

4. e.mccormick

Yes, and what is giving your trouble? This is a tutoring site...

5. anonymous

i dont understand anything at all im lost can you explain ?

6. e.mccormick

When you have something = 0 equations, you need to factor it and then find when the factors would be 0. This is sometimes called the roots, zeros, or x intercepts of a polynomial.

7. e.mccormick

So, if you factor $$8x^2 + 64x$$, what do you get?

8. anonymous

8x^2

9. e.mccormick

Um, that is the first term, but it is not the factors.

10. anonymous

ok , so can you break this down in help me step by step ?

11. e.mccormick

Well, do you know what factoring is?

12. anonymous

not a clue

13. e.mccormick

OK, if I say $$a\times b\times c$$ then a, b and c are factors. They are multiplied together. Another common use is prime factorization. Like how 15 has the prime factors of 3 and 5. So that polynomeal is the result of multiplying together something. When you un-multiply it, you are factoring it.

14. anonymous

x^2 would be the factors ?

15. e.mccormick

No, it would be something like $$(x\pm h)(x\pm k)$$ where h and k are some constants.

16. e.mccormick

If I multiply out $$(x+1)(x-3)$$ I get: $$x^2+x-3x-3$$ or: $$x^2-2x-3$$ So $$(x+1)$$ and $$(x-3)$$ are factors of $$x^2-2x-3$$. That is why factoring can be called un-multiplying.

17. anonymous

ion know i just guessed

18. e.mccormick

One big clue with this one is that each term has x in it. If you factor out the x, what would you get?

19. zzr0ck3r

when someone is helping you, and they ask you a question and you guess, it makes them not want to hep you.

20. anonymous

solve your equation step-by-step. 8x2+64x=0 Factor left side of equation. 8x(x+8)=0 Set factors equal to 0. 8x=0 or x+8=0 This should be more than enough clues :)