# MAT - Paper 2017 - Q2

## Flashcards

### 2021-10-22

What is it sometimes constructive to do with a system of equations where at least one of the entries is always zero?

Add up all the equations rather than just a pair.

When equating coefficients, what must you check?

That you’re actually equating it to something they’ve told you must exist.

If you’ve been given that

\[\frac{1}{1 + \alpha} = A + B\alpha + C\alpha^2\]
why can’t you just do

\[1 \equiv (1 + \alpha)(A + B\alpha + C\alpha^2)\]
and compare coefficients?

Because you’d end up with a cubic expression on one side, and they haven’t told you that exists.