+ Order(pow(x, 2));
result += check_series(e, 0, d, 2);
+ e = sqrt(1+x*x) * sqrt(1+2*x*x);
+ d = 1 + Order(pow(x, 2));
+ result += check_series(e, 0, d, 2);
+
symbol a("a");
e = pow(x, 4) * sin(a) + pow(x, 2);
d = pow(x, 2) + Order(pow(x, 3));
result += check_series(e, 0, d, 3);
+ symbol b("b");
+ e = log(a*x + b*x*x*log(x));
+ d = log(a*x) + b/a*log(x)*x - pow(b/a, 2)/2*pow(log(x)*x, 2) + Order(pow(x, 3));
+ result += check_series(e, 0, d, 3);
+
return result;
}