Question

Find the following by using suitable identity :-

a. (-2a – b + 5c)^2​

Answer 1

Identity: (a+b+c) ² = a² + b² + c²+ 2ab + 2bc + 2ca

(-2a)² + (-b²) + (5c) ² + 2 (-2a) (-b) +2(-b) (5c) +2(5c) (-2a)

4a+b²+ 25c²+4ab-10bc-20ac