`(2x-1)^2 - 2 (x+3)(2x-1) + (x+3)^2`
` = [ (2x-1)^2 - (x+3)]^2`
`= (2x-1-x-3)^2`
` = (x-4)^2`
` = x^2 - 2 . x . 4 + 4^2`
` = x^2 - 8x+16`
``
`2 (2x+5) - 3 (4x+1) . (1-4x)`
` = (2 . 2x + 2.5) - 3 . [ 1^2 - (4x)^2]`
` = (4x + 10) - 3 (1-16x^2)`
` = 4x + 10 - 3 . 1 + 3 . 16x^2`
` = 4x + 10 - 3 + 48x^2`
` = 48x^2 + 4x + (10-3)`
` = 48x^2 + 4x+7`