http://www.sgforums.com/forums/2297/topics/316684 en-US 60 <p>me also have exam tmr, but well</p> <p>a) x^2 + ax - b &lt; 0<br /> smiling curve smaller than 0, so roots at -2 and 4<br /> so x^2 + ax - b = (x+2)(x-4) = x^2 -2x -8</p> <p>hence a = -2,<br /> -b = -8 =&gt; b=8</p> <p>&nbsp;</p> <p>b) 2x^2 - bx + a &gt; 0 or x^2 - b/2 x + a/2 &gt; 0<br /> smiling curve again, and roots at x=-2 and x=3<br /> so x^2 - b/2 x + a/2 = (x+2)(x-3) = x^2 - 5x -6<br /> a/2 = -6 =&gt; a = -12<br /> -b/2 = -5 =&gt; b = 10</p> Tue, 06 May 2008 19:18:03 +0800 www.sgforums.com:2297:316684:8066222 eagle http://www.sgforums.com/forums/2297/topics/316684 <p>find the value of a and of b for which,</p> <p>(a) x^2 + ax &lt; b&nbsp;is only satisfied by -2 &lt; x &lt;4&nbsp;</p> <p>&nbsp;</p> <p>(b) 2x^2 + a &gt; bx is only satisfied by x &lt; -2 or x&gt;3</p> <p>&nbsp;</p> <p>Answers (a) a= -2 , b= 8&nbsp;&nbsp; (b) a=-12 , b = 2</p> <p>&nbsp;</p> <p>please lend me a hand in solving this. having an exam tomorrow, so please do state the workings clearly. thanks!</p> Tue, 06 May 2008 19:09:27 +0800 www.sgforums.com:2297:316684:8066196 bonkysleuth http://www.sgforums.com/forums/2297/topics/316684