Solve for x and y by cross- multiplication : `(i) px+qy=p-q , qx-py=p+q`

Explanation

`px+qy = p-q ->(1)`

`qx-py = p+q->(2)`


Applying cross-multiplication method,

`x/(-qp-q^2-p^2+pq) = y/(-pq+q^2+p^2+pq) = 1/(-p^2-q^2)`

`=>x/(-q^2-p^2) = 1/(-p^2-q^2)`

`=> x = (-q^2-p^2) /(-q^2-p^2) = 1`

`=>y/(q^2+p^2) = 1/(-p^2-q^2)`

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