Related Post: 4x 1 2 X 5 3 4x 2 1 3 X 5 ) = 3x 1 2 X 5 3 4 1 2 X 5 3 =- 7 4 4x 2 1 =( 2x 1 )( 3x 5 Differentiate 4x 2 1 /( 5 2x 3 3x 1 )( 4x 2 )- 5 2x 3 4 1 2 X 5 3 4 Envelopes 12 1 2 X 5 3 4 21 1 2 X 5 3 4