View Compilation Error

0_0_1727964_30581.cpp:30: error: expected init-declarator before "Q"
0_0_1727964_30581.cpp:30: error: expected `,' or `;' before "Q"
0_0_1727964_30581.cpp: In function `double sol(int)':
0_0_1727964_30581.cpp:35: error: `Q' undeclared (first use this function)
0_0_1727964_30581.cpp:35: error: (Each undeclared identifier is reported only once for each function it appears in.)