Question

the expansion form of (3a+2b-c)square..​

Answer 1

Answer:

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

$[ 3a + 2b + (-c) ]^{2}$

Let x, y ,z be 3a , 2b , -c respectively

$(x + y + z)^{2} = x^{2} + y^{2} + z^{2} + 2(xy + yz + zx)$

Putting the value of x , y , z in the above identity

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

$= 9a^{2} + 4b^{2} + c^{2} + 2[(6ab) + (-2bc) + (-3ac)]$

$= 9a^{2} + 4b^{2} + c^{2} + 2[6ab - 2bc - 3ac]$

$= 9a^{2} + 4b^{2} + c^{2} + 12ab - 4bc - 6ac$