Question

determine o valor de x para que o determinante seja igual a zero
2 × 1
3 2 -1
4 5 2

Answer 1

2 × 1
3 2 -1
4 5 2
Det = 0
8+15-4x -8+10-6x= 0
-10x +25= 0
10x = 25
x= 25/10 = 5/2 ✓

Answer 2

Por regra de Sarrus

| 2..x..1 | 2..x |
| 3..2..-1| 3..2 | = 0
| 4..5..2 | 4..5 |

8 -4x + 15 -8 + 10 - 6x = 0
-10x + 25 -6 = 0
-10x = -19
x = 19/10