# Finding length of the missing side

• October 2nd 2011, 02:01 PM
vaironxxrd
Finding length of the missing side
Even though this is geometry it comes from my Algebra 2 class.

http://img822.imageshack.us/img822/7...issingside.jpg

I believe that $2x+3$ is the With so I guess that I have to find the length?
Area : $2x^2+5x+3$

Area= L*W

Therefore $2x^2+5x+3= 2x+3$ = Length?
• October 2nd 2011, 02:04 PM
pickslides
Re: Finding length of the missing side
It should be $2x^2+5x+3= (2x+3)\times L$ now divide it out.
• October 2nd 2011, 02:06 PM
Siron
Re: Finding length of the missing side
You know the length of the rectangle is $2x+3$ and the area of the rectangle is $2x^2+5x+3$ that means the breadth of the rectangle has to look like $ax+b$, therefore:
$(2x+3)\cdot(ax+b)=2x^2+5x+3$

Determine $a$ and $b$
• October 2nd 2011, 03:31 PM
vaironxxrd
Re: Finding length of the missing side
Quote:

Originally Posted by pickslides
It should be $2x^2+5x+3= (2x+3)\times L$ now divide it out.

$2x^2=L-3x$ ?
• October 2nd 2011, 04:29 PM
skeeter
Re: Finding length of the missing side
pickslides said divide ...

$L = \frac{2x^2+5x+3}{2x+3}$
• October 2nd 2011, 04:53 PM
vaironxxrd
Re: Finding length of the missing side
Quote:

Originally Posted by skeeter
pickslides said divide ...

$L = \frac{2x^2+5x+3}{2x+3}$

$L=\frac{2x^2+3x}{1}$ or $2x^2+3x$
• October 2nd 2011, 05:18 PM
skeeter
Re: Finding length of the missing side
go learn how to do long division of polynomials ...

Polynomial Long Division
• October 2nd 2011, 07:26 PM
Quacky
Re: Finding length of the missing side
Quote:

Originally Posted by skeeter
go learn how to do long division of polynomials ...

Polynomial Long Division

Honestly I think Siron's method will suffice for now.
• October 3rd 2011, 04:02 AM
skeeter
Re: Finding length of the missing side
Quote:

Originally Posted by Quacky
Honestly I think Siron's method will suffice for now.

if you had bothered to check the link, you would have noticed that it also shows the factoring technique.
• October 3rd 2011, 05:33 PM
Quacky
Re: Finding length of the missing side
Quote:

Originally Posted by skeeter
if you had bothered to check the link, you would have noticed that it also shows the factoring technique.

I never denied that. But the subject of the page is on polynomial long division, and I think that's asking the OP to run before they walk. With the UK system, there are about 3 years of teaching between this, which is applying the knowledge of factoring, and polynomial division. (Speechless)
• October 3rd 2011, 05:45 PM
Wilmer
Re: Finding length of the missing side
Quote:

Originally Posted by Quacky
Honestly I think Siron's method will suffice for now.

Well, NO method will suffice for now; the OP does not know basics and needs classroom help, period.