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anonymous
 5 years ago
factor completely:
25s^2+420s
anonymous
 5 years ago
factor completely: 25s^2+420s

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mathteacher1729
 5 years ago
Best ResponseYou've already chosen the best response.0As a general technique for solving these problems, we know we want our answer to look like ( stuff ) * (stuff) , to be more specific, we want it to look like ( number* s plus/minus number) * ( number*s plus/minus number). In this case you can see that the 25 multiplied by s^2 can factor only into 5*5 or 1*25. (that's where the 5x comes from). From there it's filling in the steps of FOIL.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0hold the phone. it says "factor" not solve for x. you do not have an equation here so do not write x = anything!

mathteacher1729
 5 years ago
Best ResponseYou've already chosen the best response.0I would recommend checking out these videos: http://www.mathtv.com go to algebra > quadratic equation > factoring polynomials, and watch all the ones with the old guy. He is awesome. :D

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0the value of s just an extra...

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0it would help to write as \[25s^220s+4\] and recognize this as a "perfect square"

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0\[25s^2\] is the square of \[5s\] 4 is the square of 2 and \[20x =2\times 2\times 5x\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0so right away you get \[(5x2)^2\] because \[(ab)^2=a^22ab+b^2\]

mathteacher1729
 5 years ago
Best ResponseYou've already chosen the best response.0There is a nice illustration of that here: http://en.wikipedia.org/wiki/File:A_plus_b_au_carre.svg

mathteacher1729
 5 years ago
Best ResponseYou've already chosen the best response.0Oh for goodness sake... http://upload.wikimedia.org/wikipedia/commons/c/c2/A_plus_b_au_carre.svg
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