Question

http://i1084.photobucket.com/albums/j409/QRAWarrior/MATA30Y-WrongWrong-2.png

Apparently both of them are assessed as "Wrong" by the e-assignment. What exactly did I do wrong? I literally did 3 other questions like this and thought it would be fine, and all of them outputted "Wrong".

Answer 1

In the first one, when you did your partial fractions and found that B = 1, then it should be 1/x^2

Answer 2

I see that. Thanks. Is that all for that one?

Answer 3

In the second one:
\[7x^2+2x-7=A(x^2-1)+Bx(x+1)+Cx(x-1)\]
\[7x^2+2x-7=Ax^2-A+Bx^2+Bx+Cx^2-Cx\]
\[7x^2+2x-7=(A+B+C)x^2+(B-C)x-A\]
\[A+B+C=7\]
\[B-C=2\]
\[-A=-7\]

Answer 4

So
\[A=7, B=1, C=-1\]

Answer 5

Really? I don't understand where I messed up on the "Let x =" portions. I thought I did those right..

Answer 6

You wrote 7 = A+B+C but you never wrote the other two equations.