Question

(3a-7b-c)(3a -7b-c )

Answer 1

Heya there !!!
Here is the answer you were looking for:

We know that
${(a - b - c)}^{2} = {a}^{2} + {b}^{2} + {c}^{2} - 2ab + 2bc - 2ca$

Putting a = 3a
b = 7b
and c = c

${(3a)}^{2} + {(7b)}^{2} + {(c)}^{2} - 2(3a)(7b) + 2(7b)(c) - 2(c)(3a) \\ \\ = 9 {a}^{2} + 49 {b}^{2} + {c}^{2} - 42ab + 14bc - 6ac$

Hope this helps!!!

If you have any doubt regarding to my answer, please ask in the comment section.

@Mahak24

Thanks...
☺☺

Answer 2

Here is your answer>>>≥>>>>>>>>>>>>>>.....


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

putting a=3a
b=7b
c=c

(3a)^2+(7b)^2+(c)^2-2(3a)(7b)+2(7b)(c)-2(c)(3a)
=9a^2+49b^2+c^2+c^2-42ab+14bc-6ac