## likecrazy143 3 years ago What is the expression in factored form? x^2 + 13x + 42

1. henryrodriguez713

(x+6)(x+7)

2. CliffSedge

How did you get that, @henryrodriguez713 ? ( http://openstudy.com/code-of-conduct )

3. appleduardo

6+7 = 13, 6*7 = 42 :P so henry is right, thats the factored form

4. henryrodriguez713

Sorry! Went to shower. Umm... This should help you with remembering the process of factoring quadratics. AND just know that if there is no "a" it's understood to represent 1 and if it's 1 you don't really have to divide, since 6/1 is 6. $f(x)=ax^2 + bx +c$ MFDARM: My M:ultiply by a*c Father F:ind the factors of ac that add to b Drives D:ivide by a A This a <--- Red R:educe fractions Mustang M:ake into factors: put x on bottom and read up. $f(x)=ax^2 + bx +c$ $f(x)=x^2 + 13x + 42$ a=1 b=13 c=42 (Note: there is always an invisible 1 at "a") M: 1*42=42 F: 42 ** (NOTE: While getting the factors, add them and see if they add to 13)** 1 * 42 (1+42=43) NOT A FACTOR; doesn't add to 13 2 * 21 (2+42= 44) NOT A FACTOR; doesn't add to 13 3 * 14 (3+14=17) NOT A FACTOR; doesn't add to 13.( @thispointyouknowyou're close 6 * 7 (6+7=14) DING! DING! DING! Now divide by "a" $\frac{ 6}{ 1x} \frac{ 7 }{ 1x }$ = (x+6)(x+7) So, (x+6)(x+7) and if you work it out you see it adds back to the original equation. NOTE: I know it doesn't make sense to divide by a, but it will help when a is 5 or 6 or 9 and so on.