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Friday, December 02, 2005

The 200 scribe post!


December 01 (Thursday’s class):

In Thursday’s class we learned how to multiply and divide Rational Expressions.

First, Mr. Kuropatwa gave us four questions to solve, which were:

x²+5x+6 ⁄ x²-6x+5 · x²+x-30 / x²+9x+18 and the solution was:

{we ALWAYS factor and write the restrictions first}
(x+2)(x+3) / (x-5)(x-1) · (x+6)(x-5) / (x+6)(x+3)

and the restrictions are
x≠ 1, 5, -3, -6

=(x+2) (x+6) / (x+6) (x-1)

=(x+2) / (x-1)

the other questions was:

a²-3a-4 / a²+5a ÷ a²-7a+12 / a²+2a-15

we factor it:

(a-4)(a+1) / a(a+5) ÷ (a-4)(a-3) / (a+5)(a-3)

X≠ 0, -5, 3, 4

because it is dividing, we write down the first one and than in the second one we change

the numerator to the denominator and the denominator to the numerator. And change the

dividing sign to multiplying sign.

(a-4) (a+1) / a(a+5) · (a+5) (a-3) / (a-4) (a-3)
for finding the restrictions we should look at the first denominator: a(a+5) and both numerator and denominator of the second one: (a+5)(a-3) all over (a-4)(a-3)

(a+1) (a-3) / a
(a-3)

= a+1 / a _ _
Notice that here comes the big NO!

And also two other dividing questions, which I am going to write it and you, can try and solve them by your self (if you weren’t at the class)

3n+6 / 2n+2 ÷ n+2/ n²-1

and: 6x²-37x+6 / x²-9x+18 ÷ 12x²+16x-3 / 5x²-12x-9
{if you do this one, you have learned everything about it}

after this we did some Qs about solving for x: for example:

3 / x+1 = 5 / 3x-1

we cross multiply:

3(3x-1) = 5(x+1)
9x-3=5x+5
4x=8
x=2
x ≠ 1, 1,1/3

Homework is exercise. 52 omit Q.11.

Scribe for Monday is: A.Z



3 Comments:

At 12/02/2005 7:19 PM, Blogger Mr. Kuropatwa said...

Great Post Parvin!!!

Happy 200th!!

 
At 12/03/2005 1:18 PM, Blogger parvin said...

....

thanks mr. k!

 
At 12/05/2005 12:42 AM, Blogger Mr. Kuropatwa said...

Hey Parvin, that's a great link in the title to the post -- nice touch! ;-)

 

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