i have the answer but i m not enitirely sure how i got it... can somebody explain how this is done?

revising for As exam tomorrow and panicing lol

thanks!

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- Jan 8th 2009, 08:58 AMcoyoteflaresolve the inequality x^2+2x<3
i have the answer but i m not enitirely sure how i got it... can somebody explain how this is done?

revising for As exam tomorrow and panicing lol

thanks! - Jan 8th 2009, 09:04 AMrunning-gag
Hi

Inequation $\displaystyle x^2 + 2x < 3$ is equivalent to $\displaystyle x^2 + 2x - 3 < 0$

1 is solution of $\displaystyle x^2 + 2x - 3 = 0$ therefore you can factor by (x-1)

$\displaystyle (x-1)(x+3) < 0$

A product of 2 factors is negative when exactly one of them is negative and the other one positive

Review all the possible cases, build a table of signs to find the answer (Wink)