Question

please answer the question........​

Answer 1

Answer:

Ans 1 =: Using the identity.

(a+b+c)²=a²+b²+2ab+2bc+2ac

Now, put the value on the formula and execute..

→ (3a-7b-c)²=(3a)²+(-7b)²+(-c)²+2.3a(-7b)+2.(7b)(-c)+2.3b.(-c)

→(3a-7b-c)² =9a²+49b²+c²-42ab+14bc-6ac..

Answer 2

Answer:

check the given Number are in proportion or not -15:21:5:7