given a =
3 x y
9 -5 2 and det a = 150
0 4 7
find the deteminant of
-5 9 2
x 3 y
4 0 7 by properties of determinants
and
if y=6 find x of martrix a
matrix問題 !!!!!!!!!!~~~~
2012-01-08 4:41 am
回答 (2)
2012-01-08 4:48 am
✔ 最佳答案
Given 3(-5)(7) +9(4)y - (2)(4)(3) - 9(7)x = 150-105 + 36y - 24 - 63x = 150 ----------------------(*)
Determinant
= -5(3)(7) + 9(4)y - 2(3)(4) - 7(9)x
= -105 + 36y -24 - 63x
= 150 [By (*)]
If y = 6,
-105 + 36(6) - 24 - 63x = 150
x = -1
參考: Hope the solution can help you^^”
2012-01-08 5:17 am
By properties of determinants,
From matrix A, change the first and second column
Then change the first and second row
We obtain the new required matrix
The value of determinant
= (-1)(-1)det(A)
= det A
= 150
If y = 6
-105 + 36y - 24 - 63x = 150
-105 + 216 - 24 - 63x = 150
x = -1
From matrix A, change the first and second column
Then change the first and second row
We obtain the new required matrix
The value of determinant
= (-1)(-1)det(A)
= det A
= 150
If y = 6
-105 + 36y - 24 - 63x = 150
-105 + 216 - 24 - 63x = 150
x = -1
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