Which numbers cannot be used in place of x in the rational expression?

Question

-13/1-2x

AND:
Subtract. Express your results in simplest form.


x^2/x+1 - 2x+3/x+1

Answer 1

I am going to assume that you meant this for the first equation:

-13 / (1-2x)

In this case, the denominator (the bottom of the fraction) cannot equal 0 because that would make it undefined. Solve for:

1 - 2x = 0
-2x = -1
x = 1/2

Now for the subtraction:
x^2 / (x+1) - (2x+3) / (x+1)

This is easy. It's just like when you are subtracting fractions without x terms. Since the denominators are already the same, just subtract the numerators, keep the denominator the same.

(x^2 - 2x - 3) / (x+1)

Now, factor the numerator to see if you can simplify.
x^2 - 2x - 3
(x + 1)(x - 3)

Now you have:
[(x + 1)(x - 3)] / (x+1)

Divide the (x + 1) into the numerator, and you are left with (x - 3) as your answer.

If you need any more help, feel free to click on my avatar to the left of my answer and email me a question.

Answer 2

In the first rational expression, the denominator cannot be 0, since division by 0 is undefined. So what value of x would make (1 - 2x) = 0? That value is your answer.

For the second question, since the denominators are common, you can simply subtract.
(x^2 - 2x - 3) / x + 1
But you can factor the numerator:
(x - 3)(x + 1) / x + 1
You can then cancel the (x + 1) terms, leaving you with the answer.

Answer 3

dividing by zero is not allowed thus 1-2x should never be zero, 1 - 2x is zero when x = 1/2 ( 1-2x = 0 <=> 1 = 2x <=> x = 1/2 )
thus x = 1/2 can not be used.


x^2/(x+1) + 3/(x+1) -2x = { x^2 + 3x -2x(x+1) }/(x+1) =
(-x^2 + x)/(x+1) = x(1-x)/(x+1)

Answer 4

1-2x cannot be equal to 0 so x cannot be 1/2.
Put some brackets on the second equ'n.

Answer 5

1 - 2x cannot = 0

x cannot = 1/2

AND

(x^2 -2x - 3)/(x+1) = (x+1)(x-3)/(x+1) = x+3, where x cannot equal -1

Answer 6

(-13)/(1 - 2x)

1 - 2x = 0
-2x = -1
x = (1/2)

x cannot equal (1/2)

--------------------------------

((x^2)/(x + 1)) - ((2x + 3)/(x + 1))
(x^2 - (2x + 3))/(x + 1)
(x^2 - 2x - 3)/(x + 1)
((x - 3)(x + 1))/(x + 1)
ANS : x - 3

Answer 7

You're not only a nerd but also a geek I guess that makes you a neek

Answer 8

Why? Whoops I meant to say "y"

Answer 9

.5

and

(x-3)