供参考:
a/=SQR(k+m)/SQR(k+m) = a/k+m*k+m/k+m*k+m = 5 + 2 + 0 + 2 + 1 = 10
选c , 2* (3 + (3+1)* 5 + 1)
建议你直接一行一行程序运行