Q4 of 105 Page 279

Factorize the expressions and divide them as directed:

15ab (a2–7a + 10) ÷ 3b (a – 2)

In the given term


Dividend = 15ab (a2–7a + 10)


The given expression (a2–7a + 10) looks as


x2 + (a + b) x + ab


where a + b = -7; and ab = 10;


factors of 10 their sum


-1 × -10 -1-10 = -11


-2 × -5 -2-5 = -7


the factors having sum -7 are -2 and -5


(a2–7a + 10) = a2 + (-2-5)a + 10


= a2–5a – 2a + 10


= a(a – 5) – 2(a – 5)


= (a – 5)(a – 2)


Divisor = 3b (a – 2)


=


= 5a(a – 5)


Hence dividing 15ab (a2–7a + 10) by 3b (a – 2) gives out 5a(a – 5)


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