A) 10
B) \[-\]10
C) 20
D) \[-\]20
Correct Answer: B
Solution :
(b): \[ab+bc+ca\] \[=\frac{1}{2}\left[ {{\left( a+b+c \right)}^{2}}-{{\left( a+b+c \right)}^{2}} \right]\] \[=\frac{1}{2}\left[ {{0}^{2}}-20 \right]=10\]You need to login to perform this action.
You will be redirected in
3 sec