Question

. If the average of a,b,c be M and ab + be =-ca, then the average of a, b,c is (A) M (B) 3M (C) 9M (D) 27M​

Answer 1

Answer:

Correct option is

B

3M

2

Given,

3

a+b+c

=M⇒a+b+c=3M

Now, (a+b+c)

2

=a

2

+b

2

+c

2

+2(ab+bc+ca)

⇒(3M)

2

=a

2

+b

2

+c

2

+0⇒a

2

+b

2

+c

2

=9M

2

Average of a

2

,b

2

,c

2

=

3

a

2

+b

2

+c

2

=

3

9M

2

=3M

2