Finding the Change in f(x) with Varying x

[iRaid]

Homework Statement

The function f changes value when x changes from a to a+dx. Find the true change and estimated change.
f(x)=x²-x, a=3, dx=.04

a) .2;.08 b).2016;.2016 c).2016;.2 d).2016;.08

Homework Equations

The Attempt at a Solution

dy=(2x-1)dx
dy=.2
Answer = C, but idk what the first number is.

IDK what to do with that tho lol.

 

[eumyang]

Homework Statement

The function f changes value when x changes from a to a+dx. Find the true change and estimated change.
f(x)=x²-x, a=3, dx=.04

a) .2;.08 b).2016;.2016 c).2016;.2 d).2016;.08

Homework Equations

The Attempt at a Solution

dy=(2x-1)dx
dy=.2
Answer = C, but idk what the first number is.

IDK what to do with that tho lol.

The first number you get from
f(a + dx) - f(a),
it looks like.

 

[iRaid]

The first number you get from
f(a + dx) - f(a),
it looks like.

Nope I tried that, I end up getting .2416 for some reason >.<

 

[eumyang]

Try again. Find
f(3.04) - f(3).

 

[iRaid]

Lol what a fail, I was doing (3.04)²-3 not 3.04..

Thanks, kind of embarrassing.