Question

Expand (3a+2b-4c) square​

Answer 1

( 2a + 3b + 4c )²

dear , we need a formula which is

( a + b + c )² = a² + b² + c² + 2 ( ab + bc + cb )

now ,

( 2a )² + ( 3b )² + ( 4c )² + 2 { ( 2a.3b + 3b.4c + 4c.2a ) }

= 4a² + 9b² + 16c² + 2 { ( 6ab + 12bc + 8ca )}

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Answer 2

Answer:

(3a−b+4c)

2

=(3a+(−b)+4c)

2

Using, (a+b+c)

2

=a

2

+b

2

+c

2

+2ab+2bc+2ac

=(3a)

2

+(−b)

2

+(4c)

2

+2(3a)(−b)+2(−b)(4c)+2(4c)(3a)

=9a

2

+b

2

+16c

2

−6ab−8bc+24ca