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Show that each one of the following systems of linear equation is inconsistent: x + y − 2z = 5 x − 2y + z = −2 −2x + y + z = 4 - Mathematics

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प्रश्न

Show that each one of the following systems of linear equation is inconsistent:

x + y − 2z = 5

x − 2y + z = −2

−2x + y + z = 4

योग
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उत्तर

The above system can be written as:

`[(1, 1, -2),(1, -2, 1),(-2, 1, 1)][(x),(y),(z)] = [(5),(-2),(4)]`

or A X = B

`|A| = 1(-3) - 1(3) - 2 (-3) = -3 - 3 + 6 = 0`

So, A is singular. Now the system can be inconsistent, if

(adj A) × B ≠ 0

C11 = −3   C21 = −3   C31 = −3

C12 = −3   C22 = −3   C32 = −3

C13 = −3   C23 = −3   C33 = −3

(adj A) = `[(-3, -3, -3),(-3, -3, -3),(-3, -3, -3)] = [(-3, -3, -3),(-3, -3, -3),(-3, -3, -3)]`

(adj A) × (B) = `[(-3, -3, -3),(-3, -3, -3),(-3, -3, -3)] [(5),(-2),(4)] = [(-15 + 6 - 12),(-15 + 6 -12),(-15 + 6 - 12)]`

= `[(-21),(-21),(-21)]`

≠ 0

Hence, the given system is inconsistent.

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अध्याय 8: Solution of Simultaneous Linear Equations - Exercise 8.1 [पृष्ठ १५]

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आरडी शर्मा Mathematics [English] Class 12
अध्याय 8 Solution of Simultaneous Linear Equations
Exercise 8.1 | Q 4.6 | पृष्ठ १५

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