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Q3) (a) The resistance, R ohms, of a copper wire at t℃ is given by R = R^' [1 + α (t - 20)] where R^' is the resistance of the wire at 20℃ and α is the temperature coefficient of resistance of copper at 20℃ .

Given R = 16.86 ohms when t = 40℃ and R = 19.07 ohms when t = 75℃, determine the values of R^' and α. (10)

(b) Factorise fully EACH of the following

(i) 24 x⁴ y - 4x³ y² - 4x² y³ ; (3)

(ii) 3a³ b - 27 ab³. (3)