Determinant solution equation D, known d = 0, the first row a, B, C, D + X, the second row a, B, C + X, the third row a, B + X, C, D, the fourth row a + X, B, C, D

Determinant solution equation D, known d = 0, the first row a, B, C, D + X, the second row a, B, C + X, the third row a, B + X, C, D, the fourth row a + X, B, C, D

R1r4, R2R3 are obtained
a+x b c d
a b+x c d
a b c+x d
a b c d+x
R2-r1, r3-r1, r4-r1 were obtained
a+x b c d
-x x 0 0
-x 0 x 0
-x 0 0 x
C1 + C2 + C3 + C4
a+b+c+d+x b c d
0 x 0 0
0 0 x 0
0 0 0 x
So d = (a + B + C + D + x) x ^ 3
So x = 0 or x = - a-b-c-d
^-^ .

The fourth-order determinant 1 x a B C x ^ 2 A ^ 2 B ^ 2 C ^ 2 x ^ 3 A ^ 3 B ^ 3 C ^ 3 results in 0

1 1 1 1
x a b c
x^2 a^2 b^2 c^2
x^3 a^3 b^3 c^3
= (a-x)(b-x)(c-x)(b-a)(c-a)(c-b)
So x = a, B, C or D

The formula for calculating the determinant of 3x3 matrix
use
| a b c |
| d e f |
| g h i |
Does anyone know the formula of 3x3 determinant? Please list a formula with the above letters
In fact, I want to write a program to calculate the 3x3 determinant. I know how to calculate the determinant, but no matter what formula is used, the program is wrong. Can someone who knows Java help me?

It's right, but it's wrong
aei+bfg+cdh-ceg-bdi-afh
Or (AEI + BFG + CDH) - (CEG + BDI + AFH)