are my answers right?

[bailey07]

6x+5
--------
5x-7

A) f(-3) = 6(-3)+5 -13 13
---------- = ----- = -----
5(-3)-7 -22 22

B) f(-x) = 6(-x) + 5 -6x+5 6x+5
----------- = ------- = ------- (not really sure about this one)
5(-x)-7 -5x-7 5x-7

C) -f(x) = -6x+5 6x+5
------- = --------- (not real sure about this one either
-5x-7 5x-7

D) f(x+h) =6(x+h)+5 6x+6h+5
---------- = -------------



am i right..i think i have a & d right...but im not too sure about b&c...if not how do i do them
5(x+h)-7 5x+5h-7

 

[tkhunny]

\(\displaystyle f(x) = \frac{6x+5}{5x-7}\)

Very Carefully...

\(\displaystyle f(-3) = \frac{6(-3)+5}{5(-3)-7} = \frac{-18+5}{-15-7} = \frac{-13}{-22} = \frac{13}{22}\)

Very good. After that, you seem to have lost track. Do NOT let variables confuse you.

\(\displaystyle f(-x) = \frac{6(-x)+5}{5(-x)-7} = \frac{-6x+5}{-5x-7} = \frac{6x-5}{5x+7}\)

Look at that last step VERY CAREFULLY. You cannot multiply just a piece by a factor. Get the entire numerator or denominator.

\(\displaystyle -f(x) = -\frac{6x+5}{5x-7} = \frac{6x+5}{7-5x}\)

Several ways to write it. Just pick one.

\(\displaystyle f(x+h) = \frac{6(x+h)+5}{5(x+h)-7} = \frac{6x+6h+5}{5x+5h-7}\)

Where did your denominator go?

 

[stapel]

6x+5
-------- . . . <= Does this mean "f(x) = (6x + 5) / (5x - 7)"?
5x-7

A) f(-3) = 6(-3)+5 -13 13 . . . <= Does this mean
---------- = ----- = ----- . . . . . . ."f(-3) = [6(-3) + 5] / [5(-3) - 7] = 13/22"?
5(-3)-7 -22 22

...

D) f(x+h) =6(x+h)+5 6x+6h+5 . . . <= Shouldn't there be
---------- = ------------- . . . . . . . . . .denominators here?

Please review the formatting articles in the links provided in the "Read Before Posting" thread. Thank you!

Eliz.