Solve the given inequality Q. 21

[chwala]

Homework Statement

See attachment

Relevant Equations

Discriminant

Q. 21

Allow me to post using phone... Will amend/ show working when i get hold of computer.In my working I have
##5x^2 -cx^2-4x-2<0##
##56-8c<0##

...

##c>7##

Textbook says ##7>c## ...who's fooling who here?

I have seen my mistake. I am wrong...put in wrong inequality sign...
Should be ##b^2 - 4ac >0 ##

Cheers guys

 

[anuttarasammyak]

[tex](5-c)x^2-4x-2<0[/tex]
We know that 5-c<0 at least so that x^2 term does not go plus infinity as |x| goes infinity.

 

[chwala]

[tex](5-c)x^2-4x-2<0[/tex]
We know that 5-c<0 at least so that x^2 term does not go plus infinity as |x| goes infinity.

I saw my mistake. My bad. Hope you good @anuttarasammyak been with you here for some time mate ...