Expand following: (3 a-5 b-c)^{2}

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2. Polynomials

hard

Expand the following:

$(3 a-5 b-c)^{2}$

Option A

Option B

Option C

Option D

Solution

$(3 a-5 b-c)^{2}=(3 a)^{2}+(-5 b)^{2}+(-c)^{2}+2(3 a)^{2}-5 b+2(-5 b)(-c)+2(-c)(3 a)$

$\left[\because a^{2}+b^{2}+c^{2}+2 a b+2 b c+2 c a=(a+b+c)^{2}\right]$

$=9 a^{2}+25 b^{2}+c^{2}-30 a b+10 b c-6 c a$

Standard 9

Mathematics

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