Use the identity $(x + a) (x + b) = x^{2} + (a + b) x + a b$ to find the following product:
(i) $(x + 3) (x + 7)$ (ii) $(4 x + 5) (4 x + 1)$

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Solution

$(i) (x + 3) (x + 7) = x^{2} + (7 + 3) x + (3) (7)$
$= x^{2} + 10 x + 21$
$(i i) (4 x + 5) (4 x + 1) = (4 x)^{2} + 4 x (5 + 1) + (5) (1)$
$= 16 x^{2} + 24 x + 5$

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Question 2(iv)
Use the identity $(x + a) (x + b) = x^{2} + (a + b) x + a b$ to find the following products:
$(4 x + 5) (4 x - 1)$

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