Question

Expand using identity: (a - 2/5b)^3
​

Answer 1

Answer:

need to find value of (−2a+5b−3c)

2

Suitable identity is (x+y+z)

2

=x

2

+y

2

+z

2

+2xy+2yz+2xz

Here x=−2a,y=5b and z=−3c

Therefore, the value of (−2a+5b−3c)

2

is

=(−2a)

2

+(5b)

2

+(−3c)

2

+2(−2a)(5b)+2(5b)(−3c)+2(−2a)(−3c)

=4a

2

+25b

2

+9c

2

−20ab−30bc+12ac