Now can you simplify these?
(i) (x + 4) + (x − 2)
(ii) (2x + 3) + (x − 1)
(iii) (x + 1) + (x − 1)
(iv) (5x + 6y) + (2x − 3y)
(v) (x + y) + (x − y)
(i) (x + 4) + (x − 2)
= (x + 4 + x) − 2 [for any three numbers x, y, z, with y > z, x + (y − z) = (x + y) − z]
= (2x + 4) − 2
= 2x + (4 − 2)
= 2x + 2
= 2(x + 1)
(ii) (2x + 3) + (x − 1)
= (2x + 3 + x) − 1 [for any three numbers x, y, z, with y > z, x + (y − z) = (x + y) − z]
= (3x + 3) − 1
= 3x + (3 − 1)
= 3x + 2
(iii) (x + 1) + (x − 1)
= (x + 1 + x) − 1 [for any three numbers x, y, z, with y > z, x + (y − z) = (x + y) − z]
= (2x + 1) − 1
= 2x + (1 − 1)
= 2x + 0
= 2x
(iv) (5x + 6y) + (2x − 3y)
= (5x + 6y + 2x) − 3y [for any three numbers x, y, z, with y > z, x + (y − z) = (x + y) − z]
= (7x + 6y) − 3y
= 7x + (6y − 3y)
= 7x + 3y
(v) (x + y) + (x − y)
= (x + y + x) − y [for any numbers x, y, z, with y > z, x + (y − z) = (x + y) − z]
= (2x + y) − y
= 2x + (y − y)
= 2x + 0
= 2x