i. (a + b)2 = (-7 + 8)2
= 12
= 1
a2 + 2ab + b2 = (-7)2 + 2 x (-7) x 8 + 82
= 49 – 112 + 64
= 1
∴(a + b)2 = a2 + 2ab + b2
(a – b)2 = (-7 – 8)2
= (-15)2
= 225
a2 – 2ab + b2 = (-7)2 – 2 x (-7) x 8 + (8)2
= 49 + 112 + 64
= 225
∴(a – b)2 = a2 – 2ab + b2
ii. (a + b)2 = (11 + 3)2
= 142
= 196
a2 + 2ab + b2 = 112 + 2 x 11 x 3 + 32
= 121 + 66 + 9
= 196
∴(a + b)2 = a2 + 2ab + b2
(a – b)2 = (11 – 3)2 = 82
= 64
a2 – 2ab + b2 = 112 – 2 x 11 x 3 + 32
= 121 – 66 + 9
= 64
∴(a – b)2 = a2 – 2ab + b2
iii. (a + b)2 = (2.5 + 1.2)2
= 3.72
= 13.69
a2 + 2ab + b2 = (2.5)2 + 2 x 2.5 x 1.2 + (1.2)2
= 6.25 + 6 + 1.44
= 13.69
∴(a + b)2 = a2 + 2ab + b2
(a – b)2 = (2.5 – 1.2)2
= 1.32
= 1.69
a2 – 2ab + b2 = (2.5)2 – 2 x 2.5 x 1.2 + (1.2)2
= 6.25 – 6 + 1.44
= 1.69
∴(a – b)2 = a2 – 2ab + b2