Question

Q9. Write in expanded form:(7a+5b-2c)²​

Answer 1

Answer:

We have,

(3a−5b−c)

2

=(3a)

2

+(−5b)

2

+(−c)

2

+2(3a)

2

−5b+2(−5b)(−c)+2(−c)(3a)

[∵a

2

+b

2

+c

2

+2ab+2bc+2ca=(a+b+c)

2

]

=9a

2

+25b

2

+c

2

−30ab+10bc−6ca.