Expand following, using suitable identities :- (3a – 7b – c)^2 - Mathematics

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Expand following, using suitable identities :- (3a – 7b – c)2 

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Solution

It is known that,

(x + y + z)2 = x2 + y2 + z2 + 2xy + 2yz + 2zx

(3a – 7b – c)2 = (3a)2 + (-7b)2 + (-c)2 + 2(3a)(-7b) + 2(-7b)(-c) + 2(-c)(3a)

                     = 9a2 + 49b2 + c2 - 42ab + 14bc - 6ac

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Chapter 2: Polynomials - Exercise 2.5 [Page 49]

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NCERT Mathematics Class 9
Chapter 2 Polynomials
Exercise 2.5 | Q 4.4 | Page 49

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