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Mathematics 20 Online
OpenStudy (howard-wolowitz):

how to combine:

OpenStudy (howard-wolowitz):

(x+2) (x-2)

OpenStudy (solomonzelman):

difference of squares

OpenStudy (anonymous):

multiply xs and the 2s

OpenStudy (anonymous):

X x X then X x -2 then 2xX then 2 x -2

OpenStudy (solomonzelman):

\(\Large\color{black}{ \displaystyle ({\rm \color{blue}{b}}-{\rm \color{red}{a}})({\rm \color{blue}{b}}+{\rm \color{red}{a}})=}\) \(\Large\color{black}{ \displaystyle {\rm \color{blue}{b}}({\rm \color{blue}{b}}+{\rm \color{red}{a}})- {\rm \color{red}{a}}({\rm \color{blue}{b}}+{\rm \color{red}{a}})=}\) \(\Large\color{black}{ \displaystyle {\rm \color{blue}{b}}^2+{\rm \color{red}{a}}{\rm \color{blue}{b}}- {\rm \color{red}{a}}{\rm \color{blue}{b}}-{\rm \color{red}{a}}^2=}\) \(\Large\color{black}{ \displaystyle {\rm \color{blue}{b}}^2\cancel{+{\rm \color{red}{a}}{\rm \color{blue}{b}}}\cancel{- {\rm \color{red}{a}}{\rm \color{blue}{b}}}-{\rm \color{red}{a}}^2=}\) \(\Large\color{black}{ \displaystyle {\rm \color{blue}{b}}^2-{\rm \color{red}{a}}^2.}\)

OpenStudy (solomonzelman):

so, see how the middle term cancels?

OpenStudy (solomonzelman):

And this is for any "a" and "b" values. The middle term always cancels.

OpenStudy (howard-wolowitz):

making it \[x ^{2} -?\]

OpenStudy (solomonzelman):

well, we just now proved that \(\Large\color{black}{ \displaystyle ({\rm \color{blue}{b}}-{\rm \color{red}{a}})({\rm \color{blue}{b}}+{\rm \color{red}{a}})= {\rm \color{blue}{b}}^2-{\rm \color{red}{a}}^2}\)

OpenStudy (howard-wolowitz):

right

OpenStudy (solomonzelman):

\(\Large\color{black}{ \displaystyle ({\rm \color{blue}{x}}-{\rm \color{red}{2}})({\rm \color{blue}{x}}+{\rm \color{red}{2}})=??}\)

OpenStudy (solomonzelman):

just compare the form

OpenStudy (solomonzelman):

x^2 is right, and minus what ?

OpenStudy (howard-wolowitz):

2

OpenStudy (solomonzelman):

yes, so x^2-2^2

OpenStudy (solomonzelman):

which is same as what? how can you simplify 2^2 ?

OpenStudy (howard-wolowitz):

-4

OpenStudy (solomonzelman):

yes, x^2-4

OpenStudy (howard-wolowitz):

OpenStudy (solomonzelman):

I can't really see the attachment. sorry

OpenStudy (howard-wolowitz):

try zooming in plz

OpenStudy (howard-wolowitz):

go to the view tab in that doc.

OpenStudy (solomonzelman):

I think I see it

OpenStudy (solomonzelman):

\(\large\color{black}{ \displaystyle \frac{3 }{8x^3y^3} -\frac{1 }{4xy} }\) \(\large\color{gray}{ \displaystyle a.~~~~~\frac{x^2y^2-3}{4x^3y^3} }\) \(\large\color{gray}{ \displaystyle b.~~~~~\frac{2x^2y^2-3}{8x^3y^3} }\) \(\large\color{gray}{ \displaystyle c.~~~~~\frac{2}{8x^3y^3} }\) \(\large\color{gray}{ \displaystyle d.~~~~~\frac{3-x^2y^2}{4x^3y^3} }\)

OpenStudy (solomonzelman):

am I right ?

OpenStudy (howard-wolowitz):

yes

OpenStudy (solomonzelman):

okay, multiply top and bottom of the second fraction by BLANK. this BLANK has to be making the denominator of the 2nd fraction [into] the same thing as the denominator of the 1st fraction \(\large\color{black}{ \displaystyle ( }\) i.e. [into] \(\large\color{black}{ \displaystyle 8x^3y^3 }\) in the denominator \(\large\color{black}{ \displaystyle ) }\).

OpenStudy (howard-wolowitz):

right thats what i got

OpenStudy (solomonzelman):

what did you get ?

OpenStudy (howard-wolowitz):

\[\frac{ 3 }{ 8x ^{3} y ^{3}} - \frac{ 1 }{ 4xy }\]

OpenStudy (solomonzelman):

oh, OPTION D, correction. \(\large\color{red}{ \displaystyle \frac{3 -2x^2y^2}{8x^3y^3} }\)

OpenStudy (solomonzelman):

how would you make the common denominator ?

OpenStudy (solomonzelman):

\(\large\color{black}{ \displaystyle \frac{3 }{8x^3y^3} -\frac{1 \color{red}{\times 4x^2y^2}}{4xy\color{red}{\times 4x^2y^2}} }\) am I correct, or am I making a little mistake ?

OpenStudy (howard-wolowitz):

Your right!

OpenStudy (solomonzelman):

no I am not... are you sure?

OpenStudy (solomonzelman):

with this multiplication, do I get the common denominator ?

OpenStudy (howard-wolowitz):

why are you timing 4*4

OpenStudy (solomonzelman):

to get you to correct me, lol

OpenStudy (howard-wolowitz):

8-8 =0

OpenStudy (solomonzelman):

so, what should I multiply on top and bottom of the 2nd fraction then ?

OpenStudy (howard-wolowitz):

im thinking 1 so that way 1*4=4 then 8=4 equals 4... but then that wouldnt be right considering we need 8 so probbaly 4*1

OpenStudy (howard-wolowitz):

or is that wrong?

OpenStudy (howard-wolowitz):

Im going with 1

OpenStudy (solomonzelman):

\(\large\color{black}{ \displaystyle \frac{3 }{8x^3y^3} -\frac{1 \color{red}{\times \color{blue}{2}x^2y^2}}{4xy\color{red}{\times \color{blue}{2}x^2y^2}} }\)

OpenStudy (solomonzelman):

that would make it a common denominator, wouldn't it ?

OpenStudy (solomonzelman):

can you finish simplifying this fraction?

OpenStudy (howard-wolowitz):

im trying

OpenStudy (howard-wolowitz):

so im going with D considering i got 3in the numerator and 8 in the denomenator

OpenStudy (howard-wolowitz):

actually if iwent 3-2 that would be 1 so it could be A

OpenStudy (howard-wolowitz):

yeah so on top of that i'd also get 4 in the bottom so its A for sure

OpenStudy (howard-wolowitz):

@pitamar

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