## Yahoo! 3 years ago The number of real roots of eq 3x^5 + 10x^3 + 30x + 7 =0 ?

1. Yahoo!

@mukushla @experimentX @Ishaan94

2. alanli123

Solve it bro

3. Yahoo!

Any clue @alanli123

4. alanli123

Or graph it?

5. alanli123

then look at x intercepts?

6. Yahoo!

i wabt to solve this manually not by graph

7. alanli123

Ok use the rational roots theorem and plug in possible root values

8. Yahoo!

wat is that

9. alanli123

bro how old are u

10. Ishaan94

my guess is only one. and that one root should be negative.

11. Ishaan94

i used descartes rule of signs.

12. Yahoo!

hw u guys are using that rule can u teach me that @Ishaan94

13. Yahoo!

i think that method is very easy!

14. Ishaan94

i can link you, http://mathworld.wolfram.com/DescartesSignRule.html. yes it's quite easy.

15. Yahoo!

16. Yahoo!

nop i got it

17. Ishaan94

haha really? try again, http://mathworld.wolfram.com/DescartesSignRule.html

18. Yahoo!

@Ishaan94 that helps a lot.....i am happy that i learnt new concept ....thxx

19. Yahoo!

since there is no change of sign it does not have any + ve roots

20. Yahoo!

is that correct

21. Ishaan94

yes