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]

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

 

[chwala]

$$(5-c)x^2-4x-2<0$$
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 ...