https://math.semestr.ru/matrix/index.php
https://matrixcalc.org/det.html#%7B%7B1,1,-2,0%7D,%7B3,6,-2,5%7D,%7B1,0,6,4%7D,%7B2,3,5,-1%7D%7Dobtain-zeros-in-row4
https://math.semestr.ru/matrix/index.php
https://matrixcalc.org/det.html#%7B%7B1,1,-2,0%7D,%7B3,6,-2,5%7D,%7B1,0,6,4%7D,%7B2,3,5,-1%7D%7Dobtain-zeros-in-row4