Expert: Sherry Wallin - 7/20/2009

Question
QUESTION: Hello Ms. Wallin,

Can you please help me with this problems?

1) 7x^2/9y divided by [4x]/[15y^2] times [35/6xy]^-1

2) [t-2/t+3] times [t^2 + 2t-3/t^2–t-2]

3) [x^2/x+1][x+1/x+2] divided by [x/(x+1)(x+2)]

4) 3x^2-8x+4/9x^2-4 divided by 3x^2-5x-2/9x^2-3x-2


ANSWER: Margaret~
    First I need you to clearly state the problems.
1) the way it is written is saying 7(x^2/9)y divided by (4x)/(15y^2)* (35/(6xy)]^-1. I believe what you mean to say is that you have {[(7x^2)/(9y)]/(4x)/[(15y^2)]}*(35/(6xy))^-1 which is equivalent to:
[(7x^2)(15y^2)]/[(9y)(4x)]* [(6xy)/(35)] which is equivalent to:
(630x^3y^3)/(1260xy) = x^2y^2/2

It is important (especially when typing in expressions to make it clear what is multiplied and what is being divided.

Math Prof

---------- FOLLOW-UP ----------

QUESTION: Sorry, I didn't type it in correctly. I put the actual symbols in now:

1) 7x^2/9y ÷ [4x]/[15y^2]∙[35/6xy]^-1

2) [t-2/t+3] ∙ [t^2 + 2t-3/t^2–t-2]

3) [x^2/x+1][x+1/x+2] ÷ [x/(x+1)(x+2)]

4) 3x^2-8x+4/9x^2-4 ÷ 3x^2-5x-2/9x^2-3x-2


Answer
You are trying to take a fraction that is written vertically and type it horizontally which will force you to use parentheses. By just putting in the symbols but typing horizontally you need parenthesis. As it stands right now you are saying multiply 7 times x divide that answer by 9 and then multiply that result by y and I am certain that is not what you want an answer for. What you want is to multiply 7 times x and then divide that amount by the product of 9 times y which is different than what you have written. Please see attached