Using properties of determinants prove that:
[R1’ = R1 + R2 + R3]
[R1’ = R1/(5x + 4)]
[R2’ = R2 - R3]
[R2’ = R2/(x - 4)]
= (5x + 4)(x - 4)[ - (x + 4) - 2x + 2x - 0 + 0 - ( - 2x)] [expansion by first row]
= (5x + 4)(x - 4)( - x - 4 + 2x) = (5x + 4)(x - 4)2
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