50g

Hello all: I've made significant progress using my HP50G with the help I got here. I have now another question: I found how to do antiderivatives, the problem is there is no explanation as to how to enter two variables on the stack. The example is find the antiderivate of 6*t*x dx........ I know that my default is X, how do I type the t? I tried alpha t and got an error. I also know that to solve it in relation to t I change the default variable to t. Then, how do I type the X? At this moment I will be happy if I can keep X as default and find how to enter t. thank you.

John