
Originally Posted by
Jon123
hello, I am hoping someone can help me understand a step.
Q1.
y = In [ (x+2) /
sqrt (x-1)]
y = In (x+2) - 1/2 In (x-1)
dy/ dx = 1/x+2 - 1/2 (1/x-1)
Now I don't understand where, on top, x-4. How do you get that??
Answer is dy/dx = x-4 / 2(x+2)(x-1)
What about common denominator??
$\displaystyle \frac{1}{x+2}-\frac{1}{2(x-1)}=\frac{2(x-1)-(x+2)}{2(x-1)(x-2)}=\frac{x-4}{2(x-1)(x+2)}$
Another example.
Q2.
y = In [ (x+1) /
sqrt (x-1)]
answer is = x-3 / 2(x^2 -1) . how come?
Same thing as above. This is basic algebra...
Tonio
Many thanks in advance!!