Free thyroxine (free T4) tests are used to help evaluate thyroid function and diagnose thyroid diseases, including hyperthyroidism and hypothyroidism, usually after discovering that the thyroid stimulating hormone (TSH) level is abnormal. T4 and another hormone called triiodothyronine (T3) are produced by the thyroid gland.
[When the determinant of a matrix is nonzero, linear system it represents is linearly independent]. When the determinant of a matrix is zero, it rows are linearly dependent vectors, and its columns are linearly dependent vectors.
1 If you multiply a row or column by a non-zero constant, the determinant is multiplied by that same non-zero constant. 2  If you multiply a row or column by a non-zero constant and add it to another row or column, replacing that row or column, there is no change in the determinant.ick the row or column with the most zeros in it. In this case, that is the second column. For each element in the original matrix, its minor will be a 3Ã3 determinant. We'll have to expand each of those by using three 2Ã2 determinants.