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OpenStudy (anonymous):
@jim_thompson5910
jimthompson5910 (jim_thompson5910):
what do you have so far
OpenStudy (anonymous):
nothing i get confused on the simplifying
jimthompson5910 (jim_thompson5910):
When you divide two fractions, you flip the second fraction (in the bottom) and multiply like so
\[\Large
\frac{\frac{15xy^2}{x^2-5x+6}}
{\frac{5x^2y}{2x^2-7x+3}}
=
\frac{15xy^2}{x^2-5x+6}*\frac{2x^2-7x+3}{5x^2y}
\]
jimthompson5910 (jim_thompson5910):
notice how \[\Large \frac{5x^2y}{2x^2-7x+3}\] flipped
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jimthompson5910 (jim_thompson5910):
What's next?
OpenStudy (anonymous):
cross multiply?
jimthompson5910 (jim_thompson5910):
no that only works if you have 2 fractions set equal to one another
jimthompson5910 (jim_thompson5910):
focus on
\[\Large
\frac{15xy^2}{x^2-5x+6}*\frac{2x^2-7x+3}{5x^2y}
\]
jimthompson5910 (jim_thompson5910):
factor everything as much as possible
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jimthompson5910 (jim_thompson5910):
then cancel common factors
OpenStudy (anonymous):
luike where do i start im confused
jimthompson5910 (jim_thompson5910):
try factoring x^2 - 5x + 6
OpenStudy (anonymous):
idk confused
jimthompson5910 (jim_thompson5910):
find two numbers that multiply to 6 (the last number) and add to -5 (middle coefficient)
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OpenStudy (anonymous):
3
jimthompson5910 (jim_thompson5910):
what about 3?
OpenStudy (anonymous):
3x3=6
jimthompson5910 (jim_thompson5910):
3 times 3 is 9
OpenStudy (anonymous):
2*
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jimthompson5910 (jim_thompson5910):
3 times 2 = 6, good
jimthompson5910 (jim_thompson5910):
but 3 + 2 = 5
we want -5 and not +5
OpenStudy (anonymous):
not possible then
OpenStudy (anonymous):
-3 x -2
jimthompson5910 (jim_thompson5910):
yes
-3 times -2 = +6
-3 plus -2 = -5
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jimthompson5910 (jim_thompson5910):
you got it
jimthompson5910 (jim_thompson5910):
so x^2 - 5x + 6 factors to (x-3)(x-2)
jimthompson5910 (jim_thompson5910):
now to factor 2x^2 - 7x + 3, you'll have to factor by grouping
OpenStudy (anonymous):
add 7x and 2x^2?
jimthompson5910 (jim_thompson5910):
first coefficient is 2
last term is 3
2*3 = 6
you need to find two numbers that multiply to +6 and add to -7 (middle coefficient)
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jimthompson5910 (jim_thompson5910):
those two numbers are -6 & -1
jimthompson5910 (jim_thompson5910):
so break up the -7x into -6x - 1x
jimthompson5910 (jim_thompson5910):
2x^2 - 7x + 3
2x^2 - 6x - 1x + 3
jimthompson5910 (jim_thompson5910):
now you factor 2x^2 - 6x - 1x + 3 by grouping
OpenStudy (anonymous):
2x^2 -5x+3?
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jimthompson5910 (jim_thompson5910):
no
jimthompson5910 (jim_thompson5910):
2x^2 - 6x - 1x + 3
(2x^2 - 6x) + (-1x + 3)
2x(x - 3) - 1(x - 3)
I'll let you do the last step
OpenStudy (anonymous):
2x^2-5x - x-3
jimthompson5910 (jim_thompson5910):
no
jimthompson5910 (jim_thompson5910):
factor out x-3
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do you factor with the other side by cancling the x-3
jimthompson5910 (jim_thompson5910):
you factor out x-3
jimthompson5910 (jim_thompson5910):
basically follow the distributive property in reverse
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jimthompson5910 (jim_thompson5910):
so you should get (x-3)(2x-1)
jimthompson5910 (jim_thompson5910):
So if you factor everything as much as possible, you get this
\[\Large \frac{15xy^2}{x^2-5x+6}*\frac{2x^2-7x+3}{5x^2y}\]
\[\Large \frac{3*5*x*y*y}{x^2-5x+6}*\frac{2x^2-7x+3}{5x^2y}\]
\[\Large \frac{3*5*x*y*y}{(x-3)(x-2)}*\frac{2x^2-7x+3}{5x^2y}\]
\[\Large \frac{3*5*x*y*y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{5x^2y}\]
\[\Large \frac{3*5*x*y*y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{5*x*x*y}\]
jimthompson5910 (jim_thompson5910):
now cancel out common terms between the numerator and denominator
OpenStudy (anonymous):
-3 and 3 cancel out
jimthompson5910 (jim_thompson5910):
no you can't do that cancellation
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jimthompson5910 (jim_thompson5910):
3 does NOT cancel with the -3 in the "x-3". It doesn't work like that
jimthompson5910 (jim_thompson5910):
however, the two "x-3" terms cancel
there are other cancellations
OpenStudy (anonymous):
5 and 5
jimthompson5910 (jim_thompson5910):
yes, what else
OpenStudy (anonymous):
x and ys
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jimthompson5910 (jim_thompson5910):
so we have this going on....
\[\Large \frac{3*\cancel{5}*x*y*y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{\cancel{5}*x*x*y}\]
\[\Large \frac{3*x*y*y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{x*x*y}\]
\[\Large \frac{3*\cancel{x}*y*y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{\cancel{x}*x*y}\]
\[\Large \frac{3*y*y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{x*y}\]
\[\Large \frac{3*\cancel{y}*y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{x*\cancel{y}}\]
\[\Large \frac{3y}{(x-3)(x-2)}*\frac{(x-3)(2x-1)}{x}\]
\[\Large \frac{3y}{\cancel{(x-3)}(x-2)}*\frac{\cancel{(x-3)}(2x-1)}{x}\]
\[\Large \frac{3y}{x-2}*\frac{2x-1}{x}\]
jimthompson5910 (jim_thompson5910):
Now multiply straight across and rearrange terms
\[\Large \frac{3y}{x-2}*\frac{2x-1}{x}\]
\[\Large \frac{3y(2x-1)}{(x-2)x}\]
\[\Large \frac{3y(2x-1)}{x(x-2)}\]
OpenStudy (anonymous):
wow so just simplification
jimthompson5910 (jim_thompson5910):
That means
\[\Large
\frac{\frac{15xy^2}{x^2-5x+6}}
{\frac{5x^2y}{2x^2-7x+3}}
\]
simplifies to
\[\Large \frac{3y(2x-1)}{x(x-2)}\]
jimthompson5910 (jim_thompson5910):
yes that is what is stated in the instructions
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