A) 65
B) 55
C) 75
D) 85
Correct Answer: B
Solution :
a + b + c = 15 Squaring both sides, we get \[{{\left( a+b+c \right)}^{2}}~=225\] \[{{a}^{2}}+{{b}^{2}}+{{c}^{2}}+2\](ab + be + ca) = 225 \[{{a}^{2}}+{{b}^{2}}+{{c}^{2}}+2\]= \[225-2\times ~85\] = 225 ? 170 = \[\]You need to login to perform this action.
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