x^2-20x+100

Question

x^2-20x+100

zehanz · Answer

I think this has the form a²-2ab+b²=(a-b)².
Now you just have to look up what a and b are...

zehanz · Answer

@ryan123345: explaining is better than giving straight answers...

anonymous · Answer

i have to use completing the square and i got it down to that but i dont know how you are suppose to get a -20

zehanz · Answer

Look a the outer terms: x² and 100, which is 10². 
Both are squares.
That is why I said: it looks like a²-2ab+b²: outer terms are squares.
If everything goes well, then the MIDDLE term must also be right: it is 20x.
This should be 2ab. If you take a=x and b=10, you can check that the middle term is also OK!

anonymous · Answer

okay thanks ill try that

zehanz · Answer

An easy way to check: 2ab is called "double product", because it is 2 times a times b.
We have taken a=x and b=10, so the double product is 2*x*10=20x. This is just right!

So: x²-20x+100 = (x-10)²

anonymous · Answer

yeah it worked

zehanz · Answer

YW!