a) `4x^2-12x+9 = (2x)^2 - 2.2x.3 + 3^2= (2x-3)^2`
b) `4x^2+4x+1 = (2x)^2+2.2x.1 +1^2 = (2x+1)^2`
c) `1+12x+36x^2 = 1^2+2.1.6x + (6x)^2 = (1+6x)^2`
d) `9x^2-24xy+16y^2 = (3x)^2 - 2.3x.4 + (4y)^2 = (3x+4y)^2`
e) `(x^2)/4 + 2xy + 4y^2 = (x/2)^2 + 2. x/2 . 2y + (2y)^2 = (x/2 +2y)^2`
f) `-x^2+10x-25 =-(x^2 - 2.x.5 + 5^2) = -(x-5)^2`
g) `-16a^4 b^6 - 24a^5 b^5 - 9a^6 b^4`
`= -[ (4a^2 b^3)^2 + 2. 4a^2 b^3 . 3a^3 b^2 + (3a^3 b^2)^2] `
`= -(4a^2b^3 + 3a^3b^2)^2`
h) `25x^2-20xy+y^2 = (5x)^2 - 2.5x.y + y^2 = (5x-y)^2`
i) `25x^4-10x^2y+y^2 = (5x^2)^2 - 2.5x^2 .y + y^2 = (5x^2-y)^2`