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.
Since the determinant is non-zero, the vectors (1, 1) and (â3, 2) are linearly independent. Otherwise, suppose we have m vectors of n coordinates, with m < n. Then A is an nÃm matrix and Î» is a column vector with m entries, and we are again interested in AÎ» = 0.