Q5 of 105 Page 274

Factories the following expressions

a2 + 10a + 24

The given expression looks as


x2 + (a + b)x + ab


where a + b = 10; and ab = 24;


factors of 24 their sum


1 × 24 1 + 24 = 25


12 × 2 2 + 12 = 14


6 × 4 6 + 4 = 10


the factors having sum 10 are 6 and 4


a2 + 10a + 24 = a2 + (6 + 4)a + 24


= a2 + 6a + 4a + 24


= a(a + 6) + 4(a + 6)


= (a + 6)(a + 4)


Hence the factors of a2 + 10a + 24 are (a + 6) and (a + 4)


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