# transpositions

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• February 1st 2008, 05:50 AM
chrill911
transpositions
This ones beyond me!!:confused:

Make x the subject:

y=(x+4)(x+3)

if anyone can explain this one to me i would be forever grateful:)
• February 1st 2008, 05:58 AM
colby2152
Quote:

Originally Posted by chrill911
This ones beyond me!!:confused:

Make x the subject:

y=(x+4)(x+3)

if anyone can explain this one to me i would be forever grateful:)

Good question! (Star)(Star)(Star)

$y=(x+4)(x+3)\Rightarrow y=x^2+7x+12$

$x^2+7x+12-y=0$

Now, use the quadratic formula...

$x=\frac{-7 \pm \sqrt{49-4(12-y)}}{2}$

$x=\frac{-7 \pm \sqrt{1+4y}}{2}$
• February 3rd 2008, 03:20 AM
chrill911
Cheers for that!!!

I gotta admit i dont fully understand the quadratic formula, but it's a step in the right direction!! Time to hit the books and do some more research.....

Thanks a lot:)