Q4 of 42 Page 136

Let’s find the L.C.M. of the following algebraic expressions:

(a2 + 2a)2 , 2a3 + 3a2-2a, 2a4-3a3-12a2


factors of (a2 + 2a)2

= a4 + 4a2 + 4a3


= a2(a2 + 4 + 4a)


= a2(a2 + 2a + 2a + 4)


= a2(a(a + 2) + 2(a + 2))


= a2(a + 2)(a + 2)


= a2(a + 2)2


Factors of 2a3 + 3a2-2a


=a(2a2 + 3a-2)


=a(2a2 + 4a-a-2)


=a{2a(a + 2)-1(a + 2)}


=a(a + 2) (2a-1)


Factors of 2a4-3a3-14a2


=a2(2a2-3a-14)


=a2(2a2 + 4a-7a-14)


= a2(2a(a + 2)-7(a + 2))


= a2(2a-7) (a + 2)


LCM is the lowest common multiple, which is the product of all the common factors taken once and the remaining factors as it is.


the LCM of (a2 + 2a)2, 2a3 + 3a2-2a, 2a4-3a3-12a2 is a2(a + 2)2(2a-1)(2a-7).


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