Tuesday

September 16, 2014

September 16, 2014

Posted by **NaNa** on Thursday, October 11, 2007 at 1:09am.

1. f(x) 2x^2 + x - 1

Before the final step, my 'result' looked weird and I think I did something wrong in my arithmetic...someone correct me?

Here's my work...

BEGINNING STEP:

lim [2(x + deltaX)^2 - (x + deltaX) - (2x^2 + x - 1)] / deltaX

near the end step:

lim [4x + 2deltaX - 2x^2 - 1] / deltaX

Thanks

- Calculus - need help! -
**Quidditch**, Thursday, October 11, 2007 at 1:41amYou started correctly, but you must have a math error in the intermediate steps.

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

=((2x2+4(x*deltaX) + 2deltaX^2 + x + deltaX - 1) - (2x^2 + x - 1) ) /deltaX

=(4(x*deltaX) + 2*deltaX^2 + deltaX)/deltaX

=4x + deltaX + 1

limit as delatX goes to 0

=4x + 1

- Calculus - need help! -
**Quidditch**, Thursday, October 11, 2007 at 2:05amOoops!

the step before the limit statement should have read:

4x + 2deltaX + 1

**Answer this Question**

**Related Questions**

calculus - I need a step-by-step limit definition of derivative for y = ln(x).

calculus - I posted one before but this is another one of those problems that i ...

Pre-calculus. - Wesley and Delia are playing a math game. Wesley gives Delia ...

calculus - Find the derivative of the function using the definition of ...

calculus - f(x)=1/x^2 use formal definition of derivative to find slope at x=2

Calculus - If f(x) = 2 √x, use the definition of derivative to find f&#...

Calculus - (1 pt) If f(x) = 2 √x, use the definition of derivative to find...

Calculus derivatives - f(a) = a + √a (a) Find the derivative of the ...

Calculus - Find the derivative of the function using the definition of a ...

Calculus - Find the derivative of m(x)=1/(x+1) by using the definition of the ...