matlab中Explicit solution could not be found

>> syms D Cf0 Rho V Ac Gamma M A Cf T Tw P y1 y2 y3 y4 y5 y6;
[y1,y2,y3,y4,y5,y6]=solve( 'y3=89/D*Cf0*Rho*V^2/2','1/Rho*y1+1/V*y2+1/Ac*y6=0','1/P*y3+Gamma*M^