solve the inequality x^2+2x<3

• January 8th 2009, 08:58 AM
coyoteflare
solve 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!
• January 8th 2009, 09:04 AM
running-gag
Hi

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

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

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

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)