Tuesday

April 21, 2015

April 21, 2015

Posted by **Jesse** on Monday, August 13, 2007 at 10:33pm.

Find all the numbers that must be excluded from the domain of the rational expression.

x+8/x^2-16, my answer: x cant be -4 or 4

x-3/x^2+11x+24, my answer: x cant be -3 or -8

Simplify the rational expression. Find all the numbers that must be excluded from the domain of the simplified rational expression.

3x+3/15^2+21x+6 I dont understand this one.

Multiply or divide as indicated.

x^2+13x+42/x^2+x-42 * x^2-49/x^2-x-42 I dont understand this one.

(x+7)^2/x-7 / x^2-49/7x-49 This I am not too sure how to do, I know you have to flip the 2nd fraction.

Add or subtract as indicated.

x^2-2x/x^2+6x + x^2+x/x^2+6x I got x-1/x+6

Express the perimeter of the trapezoid as a single rational expression.

These are the rational expressions that are being used: x+6/x+3, 5/x+3, x+1/x+3, 5/x+3. I know you have to add each of the expressions, when I get to the end of working it out, I get x^2+x+6x+6/x+3, but thats not one of my choices. My choices are: a. 2x+17/x+3, b.4x+17/x+3, c.x+17/x+3, and d. x+14.

Simplify the complex rational expression.

4+2/x / x/4+1/8 This one I dont understand how to do it,

for

"3x+3/15^2+21x+6 I dont understand this one."

First factor it this way:

3(x+1)/[3(x+1)(5x+2)

=1/(5x+2) x cannot be -1 or -2/5

for

"Multiply or divide as indicated.

x^2+13x+42/x^2+x-42 * x^2-49/x^2-x-42 I dont understand this one. "

I wish you had used brackets, I will assume it was like this:

Multiply or divide as indicated.

(x^2+13x+42)/(x^2+x-42) * (x^2-49)/(x^2-x-42)

Everything here factors:

(x+6)(x+7)/[(x+7)(x-6)] * (x+7)(x-7)/[(x-7)(x+6)]

=(x+7)/(x-6)

you calculate the necessary restrictions

for

"(x+7)^2/x-7 / x^2-49/7x-49 This I am not too sure how to do, I know you have to flip the 2nd fraction."

I am guessing it was like this:

(x+7)^2/(x-7) ÷ (x^2-49)/(7x-49)

= (x+7)^2/(x-7) ÷ (x+7)(x-7)/[7(x-7)]

= (x+7)^2/(x-7) * 7(x-7)/[(x+7)(x-7)]

= 7 because everything cancelled

for the trapezoid question, notice that the denominators are all the same, so just add the numerators to get 2x+17 which is part of your first choice.

I am not going to guess what the last question looks like without using brackets

Retype it using brackets

Add or subtract as indicated

(x^2-2x)/(x^2+6x) + (x^2+x)/(x^2+6x) I got (x-1/x+6)

Simplify the complex rational expression.

(4+2/x) / (x/4+1/8)

Choices are: a.16, b.x/16, c.1, and d.16/x

"(x^2-2x)/(x^2+6x) + (x^2+x)/(x^2+6x) I got (x-1/x+6) "

I got (2x-1)/(x+6), check your numerators

"(4+2/x) / (x/4+1/8) "

common denominator for the top is x,

for the bottom its 8

(4x+2)/x ÷ (2x+1)/8

= (4x+2)/x * 8/(2x+1)

= 16/x

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