I think that the absolute value of the determinant is the enlargement factor of a matrix. So if ad-bc is 2.2-0.0 the factor is 4. Is that correct?

A question says "Obtain the 2 × 2 matrixMassociated with an enlargement, scale factor 2." I think that the a and d elements must be the square root of 2. Why does the answer say they are 2?