# Little Bit o' Trinomial Help.

• Jan 19th 2009, 09:52 AM
TNB
Little Bit o' Trinomial Help.
Ok, I know how to do trinomial factoring, but this one problem from my teacher's eoc review is really bugging me....

Find the value that makes this a perfect square:

n(squared)-40n+C

I just can't seem to figure out the value.

Also, can you tell me how to use math notation on this forum? Like how to input the little squared symbols, ect.
• Jan 19th 2009, 09:55 AM
Jester
Quote:

Originally Posted by TNB
Ok, I know how to do trinomial factoring, but this one problem from my teacher's eoc review is really bugging me....

Find the value that makes this a perfect square:

n(squared)-40n+C

I just can't seem to figure out the value.

Also, can you tell me how to use math notation on this forum? Like how to input the little squared symbols, ect.

The value of C is

$C = \left( \frac{-40}{2} \right)^2$

As for the math notation, if you click on the math symbols in the post, it will give you the latex code.
• Jan 19th 2009, 09:56 AM
Mush
Quote:

Originally Posted by TNB
Ok, I know how to do trinomial factoring, but this one problem from my teacher's eoc review is really bugging me....

Find the value that makes this a perfect square:

n(squared)-40n+C

I just can't seem to figure out the value.

Also, can you tell me how to use math notation on this forum? Like how to input the little squared symbols, ect.

Complete the square!

$n^2-40n+C$

$= n^2-40n +20^2-20^2+C$

$= (n-20)^2-20^2+C$

For this to be a perfect square the terms outside the bracket must disappear!

$-20^2+C = 0$

$C = 20^2$

$C=400$

To see the code for the math symbols, click on them in this post, and the code will appear. It's called LaTeX.
• Jan 19th 2009, 10:04 AM
TNB
d'oh to the nth!!!
wow. i feel reeeeeal smart now.
(Doh)

uh.....(sweatdrop) thanks anyway.
coant believe I couldn't get that....
..so embarrassed.