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add or subtract rational numbers/expressions

by tonya
(mobile)











































How do we add or subtract rational numbers/expressions with the same denominator?

Perform the indicated operation.

1. -7 1
--- + ----
8 8

2. 1 1
---- + -----
5x 5x

3. 2t - 9 t - 9
-------- - --------
t(t-3) t(t-3)

Comments for add or subtract rational numbers/expressions

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Dec 02, 2010
Add or Subtract Fractions - same denominator
by: Staff

The question:

by Tonya
(Mobile)

How do we add or subtract rational numbers/expressions with the same denominator?

Perform the indicated operation.

1. -7 . . 1
.. --- + ---
.. . 8 . . 8

2...1 . . 1
...--- + ---
.. .5x . .5x

3. 2t - 9 . . . t - 9
..--------- - --------
....t(t-3) . . .t(t-3)


The answer:

In order to add or subtract fractions, they MUST have a common denominator. Yours do.

(When you begin adding and subtracting fractions which do not have a common denominator, you must force them to have a common denominator. Otherwise you cannot add or subtract them at all.)


1. -7 . . 1 . . . . -7+1 . . .-6 . . -3
...--- + --- = . .------ = --- = ---
.. . 8 . . 8 . . .. . . 8 . . . . 8 . .. 4

2...1 . . 1 . . . . 1+1 . . . . 2
...--- + --- = . .---- = . .---
.. .5x . .5x. . . . .5x . . . . 5x

3. 2t - 9 . . . t - 9. . . .. . 2t - 9 - (t - 9)
..--------- - -------- = -------------------
....t(t-3) . . .t(t-3) . . . . . . t(t-3)

. . . 2t - 9 - t + 9 . . . . . . . 2t - t + 9 - 9
= --------------------- = ------------------
. . . . .t(t - 3) . . . . . . . . . . t(t - 3)



. . . t + 0 . . . . . . .t . . . . . . 1
= ----------- = -------- = ------
. . t(t - 3) . . . . t(t - 3) . . .t - 3




Thanks for writing.


Staff
www.solving-math-problems.com



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