Discussion in 'General' started by syntax13, Sep 25, 2007.

1. Anyone who helps will get +repped. This college algebra quiz is due in an hour and I need to verify one of the problems. Here it is:

Compute and simplify the difference quotient. [f(x+h)-f(x)] / h.

f(x) = 6x^2+9x

My answer was 6h^2 + 9h + 18x.

If this is right, just let me know, but I'm not too sure it is, so if it isn't please tell me how you got what you did.

Help a stoner out! I'll positive rep anyone who gives it a shot.

2. It's been a while since I've done math, but I got 6h + 12x + 9.

3. Thanks homie, +rep

4. Yeah Buffet that's the right answer.

Here's the work:
6(x+h)^2+9(x+h)-(6x^2+9x)/h
6(x^2+2xh+h^2)+9x+9h-6x^2-9x/h
12xh+6h^2+9h/h
6h+12x+9

I love math.

5. nice lil problem, startin to get near some calc type stuff..

heres how i did it:
(6(x+h)^2 + 9(x+h) - 6x^2 +9x) / h

expanding (x+h)^2 and multiplying by 6:
(6x^2 + 12xh + 6h^2 + 9x +9h - (6x^2 +9x)) / h

(12xh +6h^2 +9x +9h - 9x) / h

(12xh +6h^2 + 9h) / h

12x + 6h + 9