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Mathematics 17 Online
OpenStudy (anonymous):

http://gyazo.com/ebc75ca83755299f7b889645720d91ee

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

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

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)

OpenStudy (anonymous):

3

jimthompson5910 (jim_thompson5910):

what about 3?

OpenStudy (anonymous):

3x3=6

jimthompson5910 (jim_thompson5910):

3 times 3 is 9

OpenStudy (anonymous):

2*

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

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)

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?

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

OpenStudy (anonymous):

2x -1

jimthompson5910 (jim_thompson5910):

read this article http://www.regentsprep.org/regents/math/algtrig/atv1/revfactorgrouping.htm

OpenStudy (anonymous):

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

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

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

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

OpenStudy (anonymous):

and just one more http://gyazo.com/85c14cd14916032fb0641771878f1487

OpenStudy (anonymous):

@jim_thompson5910

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