Can I have a test case that uses more than one method of the tested class
Obviously yes, how will you otherwise test methods which need a specific initialization before? For example
fooCalculator = new FooCalculator(someParameters);
result = fooCalculator.Calc();
If, however, your question is "Can I have a test case that tests more than one method", then the answer is "you should avoid that", because that will typically result in too large tests. See this former question for a detailed explanation.