question_answer

11.       If \[~\times \,\$\,y=(x+y+xy-1)\]  \[(x+y+xy+1),\] then the value of  \[(4\,\$\,10)\] is

A)  2195                           

B)  2915          

C)  2951                           

D)  2955

Correct Answer: B

Solution :

: (4 10) \[=\left( 4+10+4\times 10-1 \right)\left( 4+10+4\times 10+1 \right)\] \[=\left( 54-1 \right)\left( 54+1 \right)=53\times 55=2915.\]