(i) (2x + 5)2
Comparing (2x + 5)2 with (a + b)2 we have a = 2x and b = 5
a = 2x and b = 5,
(a + b)2 = a2 + 2ab + b2
(2x + 5)2 = (2x)2 + 2(2x) (5) + 52
= 22 x2 + 20x + 25
= 22 x2 + 20x + 25
(2x + 5)2 = 4x2 + 20x + 25
(ii) (b – 7)2
Comparing (b – 7)2 with (a – b)2 we have a = b and b = 7
(a – b)2 = a2 – 2ab + b2
(b – 7)2 = b2 – 2(b) (7) + 72
(b – 7)2 = b2 – 14b + 49
(iii) (mn + 3p)2
Comparing (mn + 3p)2 with (a + b)2 we have
(a + b)2 = a2 + 2ab + b2
(mn + 3p)2 = (mn)2 + 2(mn) (3p) + (3p)2
(mn + 3p)2 = m2 n2 + 6mnp + 9p2
(iv) (xyz – 1)2
Comparing (xyz – 1)2 with (a – b)2 we have
= a + xyz and b = 1
a = xyz and b = 1
(a – b)2 = a2 – 2ab + b2
(xyz – 1)2 = (xyz)2 – 2(xyz) (1) + 12
(xyz - 1)2 = x2 y2 z2 – 2xyz + 1