`7A:`

`a) (x+3)^2 - x^2 +5x -9`

`= x^2 +6x +9 - x^2 +5x -9`

`=x^2 - x^2 + 6x +5x + 9-9`

`= 11x`

`b) (x+4)^2- (x-4)^2`

`= (x+4 + x-4). (x+4 - x+4)`

`=2x . 8`

`= 16x`

`c) x. (x-5) + (x-5)^2 - 2x^2 +15`

`= x^2 - 5x + x^2 -10x +25 -2x^2 +15`

`= x^2 + x^2 -2x^2 - 5x -10x +25 +15`

`=-15x +40`

`7B`:

`a) x^2 - (x-1)^2 +8x`

`= x^2 - x^2 +2x -1 +8x`

`= x^2 -x^2 +2x + 8x -1`

`= 10x -1`

`b) (2x-3)^2 + (2x+3)^2`

`= 4x^2 -12x + 9 + 4x^2 + 12x +9`

`= 4x^2 + 4x^2 -12x +12x + 9+9`

`= 8x^2 + 18`

`c) (4-x)^2 + x. (2x-3) -16`

`= 16 - 8x + x^2 + 2x^2 - 3x -16`

`= x^2 +2x^2 -8x -3x + 16-16`

`= 3x^2 - 11x`.