Question

If a,b,c are real numbers such that a+b+c=0 and `a^(2)+b^(2)+c^(2)=1,` then
`(3a+5b-8c)^(2)+(-8a+3b+5c)^(2)+(5a-8b+3c)^(2)` is equal to
A. 49
B. 98
C. 147
D. 294

Answer 1

Correct Answer - C
Expanding are get
`98(a^(2)+b^(2)+c^(2))-98(ab+bc+ca)`
`=98-98(-(1)/(2))`
`=147`