a: \(xy+1-x^2+y\)
\(=\left(xy+y\right)-\left(x^2-1\right)\)
\(=y\left(x+1\right)-\left(x+1\right)\left(x-1\right)\)
\(=\left(x+1\right)\left(y-x+1\right)\)
b: \(1,92\cdot34+124\cdot1,92-58\cdot1,92\)
\(=1,92\left(34+124-58\right)\)
\(=1,92\cdot100=192\)