# Fill in the blanks.(i) x2 - 18 x + 81 = (…)(ii) 4 - 36x2 = (…)(...)(iii)x2 - 14x + 13 = (…)(…)(iv) 9z2 - x2 - 4y2 + 4xy = (…)(…)(v) abc - ab - c + 1 = (…)(…)

Using the identity : a2 – b2 = (a + b)(a-b)

(i) x2 - 18x + 81 = x2 - (9x) + 81 = (x - 9)(x - 9) = (x - 9)2

(ii) (4 - 36 x2) = 4(1 - 9x2) = 4(1 - 3x)(1 + 3x)

(iii) x2 - 14x + 13 = x^(2)–(13 + 1)x + 13 = x(x - 13) - 1(x - 13) = (x - 13)(x - 1)

(iv) 9z2 - x2 - 4y2 + 4xy = 9z2 - (x - 2y)2 = (3z - x + 2y)(3z + x - 2y)

(v)abc - ab - c + 1 = ab(c - 1) - (c - 1) = (ab - 1)(c - 1)

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