Emphasize that she is doing it for herself

 

not the parents.

Make sure her present needs are met.  But she will be on her own someday.  You are helping her now but not forever.

Give her some simple task that will require effort on her part.  When she completes it (no need to be perfect), praise her and celebrate with a reward (can be an icecream, or just your cheerfulness.)

What she needs is the connection between effort and happiness.  Your standard has to match her level of effort; lower it so that her effort (not matter how meeger) can produce positive results.

Danica Mckellar has some books on "girls and math."  Hope she is still willing to read them.