Help pwease I'm lostttttttt

f(x) = x^2 + 4x - 21 = 24

the answer is (x-5)(x+9) .... Why can't it be (x+9)(x-5)?

Question

Help pwease I'm lostttttttt

f(x) = x^2 + 4x - 21 = 24

the answer is (x-5)(x+9) .... Why can't it be (x+9)(x-5)?

agent0smith · Answer

(x-5)(x+9) and (x+9)(x-5) are the exact same expression, just written in a different order. 

You can change the order of multiplication... 3*5 is the same as 5*3, they're both 15.

nincompoop · Answer

it cane be, how do you know? 
do the FOIL method and expand

anonymous · Answer

sorry for the late response i keep getting disconnected from openstudy....

anonymous · Answer

so you're saying it work either way?

anonymous · Answer

nvm it doesn't work either way it has to be -9

agent0smith · Answer

Order does not matter in multiplication.

Is 4*6 any different than 6*4?

anonymous · Answer

oh wait !!!!!!!!!!! i got it so it doesn't matter !!!! i just figured it out!!!

anonymous · Answer

x + 9 = 0 so its -9 and x - 5 = 0 so its -5!!!

anonymous · Answer

got it niceeee thanks !!!

agent0smith · Answer

x-5 = 0 means x = 5, not  -5