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Here why we are post-multiplying only, the inverse of the given matrix in the second step of the answer... But why not pre-multiplyijng?? Please explain me the logic.... why the answer will be wrong when pre-multipled??

Asked by nitishkrnehu09 | 14th Nov, 2017, 08:16: PM

Expert Answer:

begin mathsize 16px style Here comma space according space to space the space question
PA equals straight B space and space we space have space to space find space out space straight A to the power of negative 1 end exponent.
In space this space case space we space post minus multiply space by space straight A to the power of negative 1 end exponent space so space that space straight A to the power of negative 1 end exponent straight A equals straight I
PA equals straight B
PAA to the power of negative 1 end exponent equals BA to the power of negative 1 end exponent
straight P open parentheses AA to the power of negative 1 end exponent close parentheses equals BA to the power of negative 1 end exponent
PI equals BA to the power of negative 1 end exponent
straight P equals BA to the power of negative 1 end exponent

In space case space of space AP equals straight B space and space we space have space to space find space out space straight A to the power of negative 1 end exponent.
We space pre minus multiply space by space straight A to the power of negative 1 end exponent space so space that space straight A to the power of negative 1 end exponent straight A equals straight I.
AP equals straight B
straight A to the power of negative 1 end exponent AP equals straight A to the power of negative 1 end exponent straight B
open parentheses straight A to the power of negative 1 end exponent straight A close parentheses straight P equals straight A to the power of negative 1 end exponent straight B
IP equals straight A to the power of negative 1 end exponent straight B
straight P equals straight A to the power of negative 1 end exponent straight B

Hope space this space clarifies space your space doubt.
end style

Answered by Sneha shidid | 7th Dec, 2017, 02:19: PM