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Mathematics 21 Online
OpenStudy (anonymous):

2r^2-16r+32...(2r+8)(r-4)??

OpenStudy (anonymous):

can't be because if you multiply 8 by -4 you get a negative number

OpenStudy (anonymous):

so it would be + sign then?

OpenStudy (anonymous):

make your live easier by factoring out a 2 from the whole thing first, and write \[2(r^2-8r+16)\]

OpenStudy (anonymous):

so would it be (2r+8)(r+4)

OpenStudy (anonymous):

then see if you can factor \[r^2-8x+16\] as \[(r-a)(r-b)\] both numbers have to be negative, because when you multiply them together you get +16 but they add up to - 8

OpenStudy (anonymous):

no but close. they have to add up to -8, not +8

OpenStudy (anonymous):

don't forget to factor out the 2 first, as i wrote, start with \[2(r^2-8r+16)\]

OpenStudy (anonymous):

2r^2-16r+32 ok thats the original equation

OpenStudy (anonymous):

im lost on where i have to add up to -8

OpenStudy (anonymous):

right, and your job is to factor. you see that each "coefficient" is even right? so factor out a 2 first

OpenStudy (anonymous):

again make sure to start with \[2(r^2-8r+16)\]

OpenStudy (anonymous):

that is why i said you need two number whose product is +16 and whose sum is -8 in other words two numbers that when you multiply you get positive 16 but when you add you get minus 8

OpenStudy (anonymous):

oh -2 and 4?

OpenStudy (anonymous):

8 and 2?

OpenStudy (anonymous):

not 8 and 2, because although 2 times 8 is 16, 2 + 8 is 10 and you need -8 not 10

OpenStudy (anonymous):

4 and 4

OpenStudy (anonymous):

getting warmer. 4 times 4 is 16 but 4 + 4 is 8 you want minus 8

OpenStudy (anonymous):

so just make them both negative

OpenStudy (anonymous):

in other words pick -4 and -4 because if you multiply them together you get \[(-4)\times (-4)=+16\] and \[-4+(-4)=-8\]

OpenStudy (anonymous):

ugh i see now lol

OpenStudy (anonymous):

and so your "final answer" is \[2(r-4)(r-4)\]

OpenStudy (anonymous):

more succinctly written as \[2(r-4)^2\] impress your teacher by writing it with the exponent of 2.

OpenStudy (anonymous):

ok i got 2(r-4)^2 lol i see where you answered it lol

OpenStudy (anonymous):

good luck, and keep practicing!

OpenStudy (anonymous):

thanks :)

OpenStudy (anonymous):

yw

OpenStudy (anonymous):

have a good night. I think im done lol ill be back tomorrow lol

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