Question

solve it with suitable Identities​

Answer 1

Answer:

9a^2 + 49b^2 + c^2 -42ab +14bc -6ac

Step-by-step explanation:

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

(3a-7b-c)^2= {3a+(-7b)+(-c)}^2

(3a-7b-c)^2= 9a^2 + 49b^2 + c^2 +2(-21ab + 7bc- 3ac)

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

PLS MARK IT BRAINLIEST

Answer 2

Answer:

= 9a²- 49b² -c² - 42ab - 14bc - 6ca

Step by step explanation:

$(a + b + c) {}^{2} = a {}^{2} + {b}^{2} + c {}^{2} + 2ab \: + \: 2bc + 2ca$

Putting values accordingly

= (3a)² + (-7b)² + (-c)² + 2(3a)(-7b) + 2(-7b)(c) + 2(-c)(3a)

= (9a²) + (- 49b²) + ( -c²) + ( - 42ab) + ( - 14bc) + ( - 6ca)

= 9a²- 49b² -c² - 42ab - 14bc - 6ca

Hope it helps you:-)