Question

xcompus cu y=xy-3(x+y)+12

A)xcompus3=3 compus x=3

Answer 1

$x\circ 3=x\cdot 3-3(x+3)+12=3x-3x-9+12=3. \\ \\ 3\circ x=3x-3(3+x)+12=3x-9-3x+12=3.$

Cerința e demonstrată.