Question

m{-3 4} + n{4 -3}={10 -11} then find ,3m+7n =?

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Answer 1

$let \: x = m \: \: \\ \: \: \: \: y = n \\ = > - 3x + 4y = 10 \\ = > 4x - 3y = - 11 \\ = > - 12x + 16y = 40 \\ = > 12x - 9y = - 33 \\ \boxed { = > y = 1} \\ \boxed{= > x = - 2}$

$3m + 7n = \\ = > 3( - 2) + 7(1) \\ \large {\green { \boxed {\orange{ = > 1}}}}$

Answer 2

Given :  m{-3 4} + n{4 -3}={10 -11}  

To find : 3m+7n

Solution:

m{-3 4} + n{4 -3}={10 -11}

=>{-3m   4m}   + {4n   - 3n}  = { 10  - 11}

=> { -3m + 4n     4m - 3n } = { 10  , - 11 }

-3m + 4n  = 10    Eq1

4m - 3n   = - 11      Eq2

3 * eq 1  + 4 * eq2

=> -9m + 12n + 16m - 12n  = 30 - 44

=>  7m = -14

=> m =  - 2

-3(-2) +4n = 10

=> 4n = 4

=> n = 1

3m + 7n  =  3(-2)  + 7(1)  =  1

3m + 7n  =   1

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